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PubMed2025

Comprehensive profiling of lysine lactylation in Candida albicans and exploratory analysis of fluconazole tolerance associations.

UNLABELLED: Candida albicans is the primary pathogen of invasive candidiasis in most regions worldwide, but the therapy options for C. albicans infections are limited, and drug tolerance further exacerbates the treatment challenges. Lysine lactylation (Kla), a recently identified post-translational modification (PTM), is observed in numerous organisms; however, the role of Kla in C. albicans remains unknown. Hence, we report the first proteomic analysis of this specific modification in C. albicans and discuss its potential roles in drug tolerance of C. albicans. Altogether, 7,233 lactylation sites on 1,608 lactylated proteins were identified in C. albicans, with the highest degree of lactylation among the species studied so far. The further bioinformatics analysis revealed that the lactylated proteins were implicated in a variety of cellular functions with diverse subcellular localizations. Additionally, we found a unique survival mode of tolerant cells in the presence of fluconazole, which will be subject to a more thorough investigation in our future studies. This paper is the first report on the lactylome of Candida spp. and provides a reliable foundation for further research on Kla in C. albicans and other human pathogens. IMPORTANCE: This is the first report on the lactylome of Candida spp., and it provides some valuable insights for further research on lactylation in C. albicans and other human pathogens. Moreover, the observations in tolerant cells have prompted plausible hypotheses regarding the potential role of lactylation in mediating C. albicans tolerance to fluconazole, thereby offering a conceptual framework for subsequent investigations. Notably, fungal tolerance to azoles, a concept distinct from resistance, represents a critical phenomenon in C. albicans with profound clinical implications, as it directly correlates with therapeutic failure and persistent infections.

Candida albicans↗
PubMed2026

Protein persulfidation emerges as a conserved component of the redox response to DNA damage.

Genotoxic stress is frequently accompanied by alterations in cellular redox homeostasis; however, the mechanisms linking redox regulation to the DNA damage response (DDR) remain incompletely understood. Here, we investigated the early redox response to DNA damage induced by methyl methanesulfonate (MMS) in Saccharomyces cerevisiae, focusing on cysteine oxidative post-translational modifications (PTM). We show that activation of the DNA damage response is accompanied by rapid redox changes that occur in the absence of a generalized oxidative stress response. MMS exposure promotes selective remodeling of cysteine oxidative modifications, characterized by decreased free thiols, robust induction of protein persulfidation, and comparatively modest changes in sulfenylation. These alterations are accompanied by increased intracellular hydrogen sulfide levels, supporting the involvement of reactive sulfur species in the cellular response to DNA damage. Proteome-wide analyses revealed that cysteine oxidative modifications preferentially target proteins involved in central metabolism, nucleotide biosynthesis, and genome maintenance. Consistent with these observations, MMS-induced genotoxic stress promotes metabolic adaptation characterized by increased mitochondrial respiration, elevated ATP production, and mitochondrial morphological remodeling, linking bioenergetic adaptation to redox regulation. Importantly, perturbation of intracellular redox balance using N-acetylcysteine compromises survival under DNA-damaging conditions, supporting a functional role for redox signaling during the DDR. Finally, MMS treatment also induces protein persulfidation in mammalian cells. Moreover, exposure to etoposide, a mechanistically distinct genotoxic agent that induces DNA double-strand breaks through topoisomerase II inhibition, showed a similar trend, suggesting that protein persulfidation may not be restricted to alkylation-induced DNA damage. Together our findings identify protein persulfidation as a prominent component of the redox response to DNA damage and provide new insight into the functional interplay between mitochondrial metabolism, cysteine-based redox regulation, and genome maintenance.

Oxidation-Reduction↗
PubMed2025

O-GlcNAcylation of nuclear proteins in the mouse liver exhibit daily oscillations that are influenced by meal timing.

The liver circadian clock and hepatic transcriptome are highly responsive to metabolic signals generated from feeding-fasting rhythm. Previous studies have identified a number of nutrient-sensitive signaling pathways that could interpret metabolic input to regulate rhythmic hepatic biology. Here, we investigated the role of O-GlcNAcylation, a nutrient-sensitive post-translational modification (PTM) in mediating metabolic regulation of rhythmic biology in the liver. We observe daily oscillation of global nuclear protein O-GlcNAcylation in the liver of mice subjected to night-restricted feeding (NRF) using label-free global O-GlcNAc proteomics. Additional site-specific O-GlcNAc analysis by tandem mass tag mass spectrometry further supports temporal differences in O-GlcNAcylation by revealing day-night differences. Proteins involved in gene expression are enriched among rhythmically O-GlcNAcylated proteins, suggesting rhythmic O-GlcNAcylation may directly regulate the hepatic transcriptome. We show that rhythmic O-GlcNAcylation can also indirectly modulate nuclear proteins by interacting with phosphorylation. Several proteins harboring O-GlcNAcylation-phosphorylation interplay motif exhibit rhythmic O-GlcNAcylation and phosphorylation. Specifically, we show that O-GlcNAcylation occurs at a phospho-degron of a key circadian transcriptional activator, circadian locomotor output cycles kaput (CLOCK), thus regulating its stability and transcriptional output. Finally, we report that day-restricted feeding (DRF) in the nocturnal mouse significantly alters O-GlcNAcylation pattern. Whereas global O-GlcNAcylation analysis indicates dampening of global O-GlcNAcylation rhythm in mice fed under DRF, site-specific analysis reveals differential responses of O-GlcNAc sites when timing of food intake is altered. Notably, a substantial number of O-GlcNAcylation sites exhibit inverted day-night profiles when mice are subjected to DRF. This suggests the dysregulation of daily nuclear protein O-GlcNAcylation rhythm may contribute to the disruption in liver transcriptome previously observed in DRF condition. In summary, our results provide new mechanistic insights into metabolic regulation of hepatic transcriptional regulators via interplay between O-GlcNAcylation and phosphorylation and shed light on the deleterious effects of improper mealtimes.

Animals↗
PubMed2026

Post-translational modification of proteins in the human testis development pathway.

BACKGROUND: The foetal testes produce the androgens necessary to masculinise the developing embryo and support the maturation of germ cells, that will eventually develop into sperm, thus ensuring future reproductive capacity. The testes develop from the bi-potential gonads in a highly orchestrated process resulting in the differentiation of a complex tissue with multiple cellular lineages. While recent transcriptomic and chromatin-based analyses of human foetal testes have provided an unprecedented level of insight into signalling pathways activated during this process, proteomic studies of the human foetal gonads remain limited. Proteins are active molecules and post-translational modification (PTM) of proteins influences protein activity, stability and localisation. Studies have shown that PTMs regulate critical proteins in testis development, and their disruptions are implicated in congenital disorders including differences of sex development (DSD), in which sex development is atypical. Despite this, the role and regulation of protein PTM during human testis development remains poorly understood due to limited access to human foetal gonadal tissue, a paucity of large-scale proteomics studies, and a lack of robust of human gonad in vitro models. OBJECTIVE AND RATIONALE: This review aims to provide a comprehensive analysis of validated PTMs affecting proteins critical for testicular development. We discuss PTMs with evidence for a role in normal testis development, and highlight those disrupted in DSD. We review emerging techniques, including proteomic technologies and organ modelling systems that may advance our understanding of PTMs in foetal testis development. We discuss challenges that have restricted the application of these technologies and how overcoming these will significantly improve our understanding of testis development and disease, diagnostics and patient outcomes. SEARCH METHODS: We searched PubMed and the University of Melbourne library for peer-reviewed English-language studies using keywords such as phosphorylation, SUMOylation, acetylation, ubiquitination alongside each protein of interest. PTM sites in proteins involved in testis development were identified using the PhosphoSitePlus database focusing those confirmed in in vitro or animal model studies. ClinVar and the Human Gene Mutation Database were used to identify patient variants that may disrupt PTM sites. OUTCOMES: Our review finds that proteins required for human foetal testis development are subject to extensive PTM. Several PTM sites and PTM-mediated pathways [e.g. MAPK (mitogen-activated protein kinase) pathway] are disrupted in patients with DSD or related conditions. While recent advances in proteomics technologies hold considerable promise, their application to human foetal gonads has been constrained by technical, ethical, and logistical challenges. Encouragingly, emerging high-sensitivity and low-input technologies, alongside stem cell-based approaches, offer viable pathways to overcoming these barriers. WIDER IMPLICATIONS: The relationship between gene regulation, protein expression, and cellular outcome is inherently non-linear, shaped by additional regulatory layers-most notably PTMs. The contribution of PTMs to human testis development in both typical and atypical contexts is a major knowledge gap. Addressing this gap has broad clinical and biological relevance: it may help improve genetic diagnosis or shed light on how proteins or pathways critical for testis development respond to environmental signals-an increasingly pressing question as declining global fertility rates bring testicular function under greater scrutiny. REGISTRATION NUMBER: N/A.

Humans↗
PubMed2026

Clinical proteomics in inborn errors of metabolism: from biomarker discovery to implementation.

INTRODUCTION: Inborn errors of metabolism (IEMs) are rare, heterogeneous disorders traditionally diagnosed through genetic testing, enzyme assays, and metabolite measurements. However, these tools often do not fully explain phenotypic variability, organ involvement, disease progression, or treatment response. Clinical proteomics provides a complementary functional layer by capturing changes in protein abundance, proteoforms, post-translational modifications (PTM), and biological pathways, offering insights beyond genotype- and metabolite-based approaches. AREAS COVERED: This review examines the role of high-resolution mass spectrometry and computational proteomics in biomarker discovery and clinical decision-making for IEMs. It focuses on their contribution to diagnosis, variant interpretation, patient stratification, and treatment monitoring. Disease-specific applications are discussed, with the strongest evidence in lysosomal storage disorders, mitochondrial diseases, congenital disorders of glycosylation, and selected neurodegenerative or renal metabolic conditions. The literature search was performed in PubMed, Scopus, Web of Science, and Google Scholar, covering peer-reviewed articles available up to 2026, with emphasis on methodological advances and translational applications in clinical proteomics for IEMs. EXPERT OPINION: Proteomics will not replace established diagnostic tools, but it can help address clinically actionable questions in selected contexts. Translation into clinical practice will require standardized workflows, multicenter validation, clinically anchored endpoints, and integration with other omics approaches.

Humans↗
PubMed2026

Integrative proteomics and bioinformatics pipelines for PTM profiling.

Post-translational modifications (PTMs) regulate protein function across all life forms and allow plants to respond rapidly to biotic and abiotic stress. Over 450 PTM types have been described across organisms, of which 23-33 have been experimentally confirmed in plants, including phosphorylation, acetylation, methylation, glycosylation, ubiquitination, and sumoylation. These modifications are highly dynamic and often reversible, and frequently act in combination, or "crosstalk," to fine-tune cellular processes. Advances in high-resolution mass spectrometry and large-scale genome sequencing continue to expand the catalogue of known PTM sites, while machine learning and deep learning approaches increasingly support prediction of PTM site localization and function. Unlike broader surveys of plant PTMs, this review focuses specifically on O-phosphorylation and Lys-N(ε)-acetylation, the two best-characterized and most extensively crosstalking PTMs in plants, and integrates four perspectives: the historical development of proteomic and bioinformatics approaches to these modifications; current mass spectrometry-based workflows and enrichment strategies; the bioinformatics tools and databases available for their analysis; and the technical and species-related challenges, particularly in non-model plants, that currently limit their study. We close by outlining priority directions for future research, including multi-omics integration, AI-based prediction, and the translation of PTM knowledge into crop stress resilience and breeding applications.

Protein Processing, Post-Translational↗
PubMed2026

Comprehensive multi-post-translational modifications profiling reveals age-associated remodeling in skeletal muscle.

Sarcopenia, characterized by the progressive loss of skeletal muscle mass and function, is a major hallmark of aging. Post-translational modifications (PTMs) play essential roles in regulating protein activity and cellular homeostasis; however, how multiple PTMs are remodeled during skeletal muscle aging remains incompletely characterized. Here, we performed comprehensive multi-layered proteomic profiling of skeletal muscle from young (3-month-old) and aged (24-month-old) mice, systematically quantifying the global proteome together with five major PTMs: acetylation, phosphorylation, N-glycosylation, O-glycosylation, and ubiquitination. In total, we identified 5 337 proteins and mapped thousands of PTM sites, generating an integrated atlas of age-associated proteomic and PTM remodeling in skeletal muscle. Pathway enrichment analyses revealed distinct modification-specific patterns: acetylation and phosphorylation were predominantly associated with metabolic and mitochondrial-related pathways; N-glycosylation was enriched in immune- and secretory pathway-related processes; O-glycosylation was associated with muscle contraction-related pathways; and ubiquitination was preferentially linked to cytoskeletal organization in muscle cells. Correlation analyses further uncovered diverse association patterns among different PTMs across protein- and modification-level datasets. Phosphorylation and ubiquitination exhibited consistent positive associations, whereas acetylation and ubiquitination showed both inverse and concordant co-variation patterns across subsets of proteins. Phosphorylation and O-glycosylation displayed heterogeneous association patterns across different proteins, and acetylation and phosphorylation demonstrated positive correlations with distinct age-associated directional changes across protein subsets. Together, these results provide a comprehensive, multi-dimensional view of age-associated remodeling of the skeletal muscle proteome and multiple PTM layers, offering a valuable resource for understanding molecular alterations accompanying muscle aging and sarcopenia.

Animals↗
PubMed2026

Spatial Proteomics of the Normal Breast Collagen Stroma: Links to Density and Body Mass Index.

Collagen breast stroma can become a breast cancer risk factor, yet proteomic regulation of normal breast stroma remains poorly defined. This study evaluates the spatial regulation of the collagen proteome from normal breast tissue. Normal breast tissue sections from the Susan G. Komen tissue bank were used (n = 40), with data including genetic ancestry (n = 20 African ancestry; n = 20 European ancestry), body-mass-index (BMI), age, and mammogram density by the Breast Imaging Reporting and Data System (BI-RADS). 10-plex cell marker staining showed CD44 and COL1A1 markers modulated with BMI. Collagen fiber widths by second harmonic generation microscopy contrasted in BMI categories by genetic ancestry. Targeted extracellular matrix proteomics mass spectrometry imaging showed the collagen alpha-1(I) chain proteome was spatially heterogeneous across the normal breast microenvironment with site-specific post-translational modification of proline hydroxylation. Signatures computationally extracted from stroma-rich regions reported that 47 collagen peptides distinguished BI-RADS categories (area under the receiver operating curve >0.7; p-value >0.05). Multivariate modeling of collagen peptides, fiber metrics, and clinical features supported a strong positive association with BMI as a determinant of collagen alterations in the normal breast. This study provides a foundation for larger studies investigating the clinical value of spatial collagen proteome alterations in human breast.

Humans↗
PubMed2026

Proteomics-based approaches to neutrophil biology.

INTRODUCTION: Neutrophils are central effectors of innate immunity and key contributors to inflammation, host defense, and tissue injury across a wide range of physiological and pathological contexts. Due to their short lifespan, rapid activation, and extensive post-translational regulation, comprehensive molecular characterization of neutrophil function requires approaches that go beyond transcriptomics or marker-based analyses. AREAS COVERED: This review summarizes how proteomic technologies have advanced the understanding of neutrophil biology by enabling unbiased, system-wide profiling of protein abundance, subcellular organization, post-translational modifications, and functional heterogeneity. We discuss global and subcellular proteomics, PTM-centric analyses, and emerging low-input and single-cell proteomic strategies, highlighting recent studies of infection, cancer, metabolic disorders, aging, autoimmune disease, and inflammation. The literature covered includes current large-scale quantitative proteomics, targeted PTMs, and integrative multi-omics studies in both human samples and relevant experimental models. EXPERT OPINION: Proteomics has established neutrophils as highly plastic and context-dependent cells whose functions are governed by coordinated remodeling of signaling, metabolism, and effector pathways. Future progress will depend on expanding neutrophil-specific PTM maps, improving low-input workflows, and integrating single-cell and spatial proteomics. Together, these advances are expected to redefine neutrophil functional states and accelerate translation toward clinically meaningful biomarkers and therapeutic strategies.

Humans↗
PubMed2024

On the Hunt for the Histone Code.

Our genome is not made of naked DNA but a fiber (chromatin) composed of DNA and proteins packaged into our chromosomes. The basic building block of chromatin is the nucleosome, which has two copies of each of the proteins called histones (H2A, H2B, H3, and H4) wrapped by 146 base pairs of DNA. Regions of our genetic material are found between the more open (euchromatin) and more compact (heterochromatin) regions of the genome that can be variably accessible to the underlying genes. Furthermore, post-translational modifications (PTMs) on histones, such as on H3, are critical for regulating chromatin accessibility and gene expression. While site-specific antibodies were the tool of choice for histone PTM analysis in the early days (pre-2000s), enter Don Hunt changing the histone PTM field forever. Don's clever thinking brought new innovative mass spectrometry-based approaches to the epigenetics field. His lab's effort led to the discovery of many new histone modifications and methods to facilitate the detection and quantification of histone PTMs, which are still considered state of the art in the proteomics field today. Due to Don's pioneering work in this area, many labs have been able to jump into the epigenetics field and "Hunt" down their own histone targets. A walkthrough of those early histone years in the Hunt Lab is described by three of us who were fortunate enough to be at the right place, at the right time.

Animals↗
PubMed2026

Comprehensive Landscape of Post-Translational Modification Alterations in Nephrolithiasis Revealing Activation of Multiple Cell Death Pathways.

Nephrolithiasis is a common urinary disorder characterized by high prevalence and recurrence, but the molecular mechanisms underlying calcium oxalate (CaOx)-crystal-induced renal injury remain incompletely understood. We applied integrated proteomic, phosphoproteomic, acetylomic, and lactylomic analyses to kidney tissues from a mouse model of CaOx nephrolithiasis followed by bioinformatic analysis and experimental validation. We identified 658 differentially expressed proteins, 735 differential phosphorylation sites, 335 differential acetylation sites, and 113 differential lactylation sites. Functional enrichment indicated immune activation, fibrotic remodeling, and alterations in PI3K-Akt, NOD-like receptor, p53, and Toll-like receptor signaling together with changes in fatty acid degradation, the tricarboxylic acid cycle, and glycolysis. Kinase activity prediction suggested the relative activation of multiple cyclin-dependent kinases. Proteins associated with ferroptosis, autophagy, necroptosis, and pyroptosis, including ACSL4, BNIP3, RIPK3, and GSDMD, showed coordinated abundance and modification changes. Several candidate sites, including MTOR_S1849, GCLM_K94, GCLM_S59, and GSS_K172, were also dysregulated. These data provide a multiomics resource for CaOx nephrolithiasis and identify candidate PTM events and regulatory pathways for future mechanistic validation.

Animals↗
PubMed2026

Dynamic lysine acetylation and succinylation of platelet proteins regulates platelet storage lesion: mechanistic insights from multi-omics.

OBJECTIVES: Platelet storage lesion (PSL) severely impairs platelet function during storage, presenting a major hurdle in transfusion medicine; however, the dynamic interplay between global proteomic changes and post-translational modifications (PTMs) underlying these functional deteriorations remains insufficiently characterized. Here, we report the first comprehensive multi-omics analysis integrating global proteomics, acetylomics, and succinylomics to dissect the molecular dynamics during platelet storage. METHODS: We performed quantification of global proteomics, acetylome and succinylome based on TMT-labeled LC-MS/MS analysis, combined with antibody-affinity enrichment and purification. Dynamic molecular changes and functional transformation of platelet were also characterized under proper conditions stored for 1, 3, 5, 7 days, respectively. RESULTS: We systematically characterized 3,609 proteins, 1,308 acetylation sites, and 1,947 succinylation sites across multiple storage time points (D1, D3, D5, D7). We distinct temporal patterns of post-translational modifications, with succinylation showing more extensive coverage than acetylation in platelets. Pathway enrichment analysis revealed extensive metabolic reprogramming involving complement activation, energy metabolism, and cellular detoxification processes. The identification of specific motif patterns provided mechanistic insights into the functional specificity of these modifications. Random forest machine learning identified 20 core regulatory proteins representing critical nodes in PSL development. Furthermore, we employed real - time quantitative polymerase chain reaction (RT - QPCR) to measure the expression levels of key genes related to platelet function and PTM - associated pathways. CONCLUSION: By mapping the interplay between proteomic abundance shifts and PTM dynamics, this study provides a multidimensional understanding of PSL, establishing a foundational framework for optimizing storage protocols and enhancing transfusion safety.

Blood Platelets↗
PubMed2026

A translocation within the Ogataea species complex alters local subtelomeric chromatin while maintaining overall genome organization.

Eukaryotic genomic DNA is packaged in the nucleus as chromatin-a DNA-protein aggregate regulating genome function, including transcription. Chromatin is classified as either active euchromatin or silent heterochromatin, with each marked by distinct histone post-translational modifications (PTMs). Chromatin composition also mediates genome organization, including how heterochromatin aggregates at the nuclear periphery while euchromatin localizes to the nucleus center. In fungi, heterochromatic loci cluster, including independent centromere and telomere clusters that form the Rabl chromosome conformation. However, it is unknown if chromatin composition and genome organization are conserved in closely related fungi, and how these features are impacted by large-scale chromosomal rearrangements. Here, we examined differences in histone PTM deposition, gene expression, and genome organization in 2 yeast species from the order Pichiales, which diverged from the common ancestor shared with Saccharomyces cerevisiae more than 200 million years ago. We focused on Ogataea polymorpha, which is used for industrial protein production, and Ogataea haglerorum, an isolate of which harbors a translocation between chromosomes 1 and 6. We show that the enrichment of 3 activating PTMs-the trimethylation of lysine 4 of histone H3 (H3K4me3) and the acetylation of lysine 9 of histone H3 (H3K9ac) or lysine 16 of histone H4 (H4K16ac)-are similar genome-wide, yet gene orthologs have distinct chromatin and expression patterns. While both Ogataea genomes organize into a Rabl conformation, the O. haglerorum translocation alters subtelomeric chromatin composition and expression of genes affected by the translocation. Our work highlights the genome function differences that occur on a microevolutionary scale.

Genome, Fungal↗
PubMed2025

Genome-Wide Profiling of Histone Modifications in Fission Yeast Using CUT&Tag.

Eukaryotic DNA is organized in the nucleus in the form of chromatin. Nucleosomes, the fundamental unit of chromatin, are subject to many posttranslational modifications (PTMs) as well as compositional variations through incorporation of histone variants. These alterations play important roles in regulation of genome structure and activity. Genome-wide profiling of these regulatory features is essential for understanding of genome function. Chromatin immunoprecipitation coupled with next-generation sequencing (ChIP-Seq) is a widely used method to assay genome-wide localization in fission yeast but suffers from the requirement for a large amount of input chromatin, antibodies, and a cumbersome experimental pipeline. New methods such as Cleavage Under Targets and Tagmentation (CUT&Tag), which combine the specificity of targeted cleavage and adapter insertion with the sensitivity of next-generation sequencing, enable identification and characterization of various epigenetic marks affording low input requirement as well as more streamlined protocols. However, these approaches have not been adapted for use in fission yeast, Schizosaccharomyces pombe. Here, we describe an adapted CUT&Tag protocol for epigenomic profiling in fission yeast using the heterochromatin-associated histone H3K9 methylation PTM for benchmarking.

Schizosaccharomyces↗
PubMed2025

Systematic Identification of Microtubule Posttranslational Modification "Readers" by Quantitative Proteomics.

Microtubules, dynamic polymers assembled from α, β-tubulin dimers, contribute to myriad cellular processes. This is largely attributed to microtubule-associated proteins (MAPs). How MAPs selectively bind microtubules to carry out various functions is not known. The "Tubulin Code" theory proposes that posttranslational modifications (PTMs) of microtubules serve as signs that can be read by specific MAPs, thereby conferring specific functional properties to the microtubules. In support of this hypothesis, "reader" MAPs have been identified for various tubulin PTMs, but, until recently, no systematic screening had been performed to identify readers in an unbiased manner. We addressed this by developing a reader identification pipeline that uses quantitative mass spectrometry to interrogate the microtubule proteome of cells programmed to express specific PTMs. This pipeline can be used to identify readers for any tubulin PTM from various cell types as long as the writer enzymes are known. We also provide an alternative, complementary approach to obtain modified microtubules using a generic writer enzyme in vitro.

Protein Processing, Post-Translational↗
PubMed2026

A Translocation within the Ogataea Species Complex Alters Local Subtelomeric Chromatin while Maintaining Overall Genome Organization.

Eukaryotic genomic DNA is packaged in the nucleus as chromatin - a DNA-protein aggregate regulating genome function, including transcription. Chromatin is classified as either active euchromatin or silent heterochromatin, with each marked by distinct histone post-translational modifications (PTMs). Chromatin composition also mediates genome organization, including how heterochromatin aggregates at the nuclear periphery while euchromatin localizes to the nucleus center. In fungi, heterochromatic loci cluster, including independent centromere and telomere clusters that form the Rabl chromosome conformation. However, it is unknown if chromatin composition and genome organization are conserved in closely related fungi, and how they are impacted by large-scale chromosomal rearrangements. Here, we examined differences in histone PTM deposition, gene expression, and genome organization in two yeast species from the order Pichiales, which diverged from the common ancestor shared with Saccharomyces cerevisiae more than 200 million years ago. We focused on Ogataea polymorpha, which is used for industrial protein production, and Ogataea haglerorum, an isolate of which harbors a translocation between chromosomes 1 and 6. We show that the enrichment of three activating PTMs - the trimethylation of lysine 4 of histone H3 (H3K4me3) and the acetylation of lysine 9 of histone H3 (H3K9ac) or lysine 16 of histone H4 (H4K16ac) - are similar genome-wide yet individual gene orthologs have distinct chromatin and expression patterns. While both Ogataea genomes organize into a Rabl conformation, the O. haglerorum translocation alters subtelomeric chromatin composition and expression of genes affected by the translocation. Our work highlights the genome function differences that occur on a microevolutionary scale.

Ogataea↗
PubMed2025

Proteomic Characterization of the Rhesus Macaque Lens Nucleus: Similarity to Human Lens, Age Effects on Protein Solubility, and Trends in Post-Translational Modifications.

PURPOSE: Proteomes of lens nuclei from young (4 years old) and old (15-16 years old) rhesus macaques (Macaca mulatta) were analyzed to determine similarity of the proteomic profile to that of human lenses, age-related differences in protein solubility, and association of various post-translational modifications with age and protein solubility. METHODS: Lens core proteins were separated into water-soluble and water-insoluble fractions using aqueous buffer and centrifugation. The water-insoluble fraction was solubilized using sodium dodecyl sulfate (SDS). Proteins were processed using S-trap columns, and peptide digests were analyzed using high-resolution, label-free data-dependent acquisition (DDA) proteomics. Open modification searches were performed using MSFragger to identify possible post-translational modifications (PTMs). The number of modified peptide tandem mass spectra confidently assigned to samples by age or solubility were compared to find PTMs with statistically significant count differences. RESULTS: The overall proteomic profile of rhesus macaque lenses was very similar to human lenses, consisting of 80.2% crystallins, 1.1% beaded filament proteins, and 18.7% other proteins. The crystallin fraction consisted of 27% alpha crystallins, 67.6% beta/gamma crystallins, and 5.4% taxon-specific psi crystallin. Glycolytic enzymes, beta/gamma crystallins, and a few glutathione-related enzymes were found to have age-related shifts to the water-insoluble fraction. There were significant differences in deamidation, dioxidation, carbamylation, carboxymethylation, and trioxidation based on age and/or solubility of proteins. CONCLUSIONS: These data indicate a high level of conformity between rhesus macaque and human lens proteomes, and a few key differences. We identified several age-related differences in protein solubility and PTM that may contribute to lens pathology.

Animals↗
PubMed2026

Lysine iminylation derived from ω-3 polyunsaturated fatty acids.

Protein posttranslational modifications (PTMs) play a central role for regulating protein function and cellular processes, with many PTMs arising from reactions with electrophilic metabolites. Here we extend the known landscape of PTMs with the identification of "lysine C3-iminylation," the conjugation of protein lysine residues with propionaldehyde. To stabilize iminylation for mass spectrometric analyses and distinguish it from other isomeric PTMs, we developed a fixation and stable-isotope labeling approach based on parallel reduction of proteome with sodium borohydride and borodeuteride. Analyses of protein hydrolysates confirmed the presence of C3-iminylation in Caenorhabditis elegans and mouse. Additionally, proteomics results demonstrated specificity of this PTM in vitro and in vivo and revealed C3-iminylation in proteins related to critical metabolic pathways. Importantly, collective evidence from isotope tracing as well as genetic, dietary, and pharmacological manipulation experiments uncovered that C3-iminylation originates from cytochrome P450 (CYP)-mediated oxidation of omega-3 fatty acids. Correspondingly, C3-iminylation levels were elevated in C. elegans daf-2(e1370) mutants, an aging model, in which CYP activity is generally increased. These findings not only expand our understanding of the biochemical diversity of PTMs but also underscore the complex interplay between lipid metabolism and protein modifications, enabling further exploration of their biological and clinical implications.

Animals↗