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Genomic and functional characterization of sugar transporters reveals potential roles in sugar accumulation in a modern sugarcane cultivar.

Sugarcane (Saccharum spp.) is a globally important sugar crop whose productivity depends on efficient sugar transport from source to sink organs. However, systematic identification and functional characterization of sugar transporters (STs) in sugarcane cultivars remain limited. Here, we identified 190 non-redundant ST genes in sugarcane cultivar Guitang 42 (GT42) and phylogenetically classified them into nine groups within the Monosaccharide Transporter (MST), Sucrose Transporter (SUT), and Sugars Will Eventually be Exported Transporters (SWEET) families. Comparative evolutionary analysis revealed significant lineage-specific expansions in the PMT, STP subfamilies, and SWEET families compared to diploid and wild relatives, likely driven by polyploidization and intensive selection for sugar yield. Transcriptomic profiling across tissues and internode elongation stages demonstrated marked tissue-specific and developmental expression patterns. Yeast complementation assays confirmed the transport activity of candidate MSTs, SUTs and SWEETs, with confocal microscopy verifying their distinct subcellular localization at the plasma membrane, tonoplast, or endoplasmic reticulum. Furthermore, transient overexpression of several candidate transporters (ScSWEET4-T2, ScSWEET15, and ScTST4-T1) in Nicotiana benthamiana modulated soluble sugar accumulation, and their expression in sugarcane protoplasts activated key sugar-responsive marker genes (ScGPT2 and ScWIP4). Together, our study establishes a systematic genomic framework and identifies candidate functional transporters that govern sugar partitioning and storage, providing valuable genetic targets for molecular breeding and quality enhancement in sugarcane.

Functional characterization

Genome-wide characterization of the sugar transporter protein family identifies candidate genes for bacterial wilt resistance breeding in tobacco.

Sugar transporter proteins (STPs) play pivotal roles in hexose allocation and plant stress responses. However, systematic characterization of the STP family in tobacco (Nicotiana tabacum) and its involvement in Ralstonia solanacearum resistance remains unclear. In this study, 37 NtSTP genes were identified and classified into six groups, with Group VI being the most conserved and Group V exhibiting dicot-specific expansion. Gene structure and conserved motif analyses revealed that most NtSTP members possess the typical MFS_STP domain, although variations in exon-intron organization and motif composition suggested functional divergence. Tandem duplication (TD) served as the primary driver of NtSTP family expansion, and Ka/Ks values of all paralogous pairs were less than 1, indicative of purifying selection. Promoter cis-element analysis revealed a complex regulatory network involving hormone signaling (ABA, JA, SA, GA, ET), stress responses, and light signaling. RT-qPCR expression profiling revealed that ten NtSTP genes (NtSTP1, 5, 7, 21, 22, 24, 26, 27, 28, and 29) exhibited significant transcriptional upregulation upon R. solanacearum infection. Specifically, NtSTP5, NtSTP7, NtSTP21, NtSTP22, NtSTP24, NtSTP26, and NtSTP27 peaked at 12 h post-inoculation (hpi), whereas NtSTP1, NtSTP28, and NtSTP29 reached their highest expression levels at 24 hpi. By contrast, NtSTP6, NtSTP13, and NtSTP30 displayed reduced expression upon R. solanacearum infection. These expression patterns indicate functional diversification within the NtSTP family and imply that these members may be transcriptionally modulated during plant responses to R. solanacearum. The present work provides preliminary and valuable candidate gene resources that may facilitate future disease resistance breeding programs in tobacco.

NtSTP gene family

Phosphorylation and ubiquitination coordinate homeostasis of a tomato transporter responsible for fruit sugar accumulation.

Sugar transport mediated by different transporters is essential for maintaining sugar homeostasis in plants. Here, we report that phosphorylation and ubiquitination coordinate the homeostasis of a tomato (Solanum lycopersicum) sugar transporter SlSWEET16, revealing a new aspect of plant sugar homeostasis. SlSWEET16 is localized to plasma membrane and functions as a mono- and disaccharide transporter. SlSWEET16 mediates cellular sugar efflux, and CRISPR/Cas9-mediated knockout of SlSWEET16 leads to increased fruit sugar accumulation. Strikingly, the C-terminus of SlSWEET16 is subjected to both phosphorylation and ubiquitination. Two protein kinases including SlSnRK2.3 and SlSnRK2.4 associate with the C-terminus of SlSWEET16, resulting into an increase in the stability of SlSWEET16. Meanwhile, the C-terminus of SlSWEET16 also interacts with an E3 ubiquitin ligase SlTT3.1L2, which decreases the stability of SlSWEET16. SlSnRK2.3 and SlSnRK2.4 inhibit fruit sugar accumulation, whereas SlTT3.1L2 promotes it. Mutations of phosphorylated or ubiquitinated residues in SlSWEET16's C-terminus further corroborate the contribution of phosphorylation and ubiquitination to the stability of SlSWEET16 and fruit sugar accumulation. Our results reveal a multiple-protein regulatory module that integrates different post-translational modifications to control transporter-mediated fruit sugar accumulation.

Solanum lycopersicum

The novel transcriptional activator Bhr1 combining NTPase and Zn(II)2Cys6 DNA-binding domains controls (hemi-)cellulase response to mannose-rich substrates in the white-rot fungus Dichomitus squalens.

The regulatory landscape responsible for lignocellulose degradation in white-rot basidiomycete fungi remains largely unexplored. In this study, we characterize a novel transcriptional activator, Bhr1, in the white-rot fungus Dichomitus squalens. Bhr1 exhibits an unusual domain architecture that combines a septin-like P-loop NTPase fold with Zn(II)2Cys6 DNA-binding domains and plays a critical role in activating (hemi-)cellulase enzyme production when D. squalens is exposed to mannose-rich substrates. Using CRISPR/Cas9-mediated gene editing, we generated a bhr1 disruption mutant that displayed distinct phenotypes and enzyme activity profiles on mannose and guar gum compared to the wild type. RNA sequencing data indicate that Bhr1 induces specific (hemi-)cellulase-encoding genes without altering the expression of genes encoding sugar transporters or sugar metabolic enzymes. Phylogenetic analyses show that Bhr1 is basidiomycete specific and largely restricted to saprotrophic and plant-associated Agaricomycetes fungi. Based on the domain architecture of Bhr1 and the effects of its disruption in D. squalens, our findings reveal a lineage-specific regulatory innovation in basidiomycetes that is distinct from those described in ascomycetes. Elucidating the function and evolutionary conservation of Bhr1 advances our understanding of lignocellulose degradation at the molecular level in basidiomycete fungi and may inform studies of their ecological adaptation and the development of biotechnological applications.IMPORTANCEUnderstanding the transcriptional regulatory mechanisms in white-rot fungi, such as Dichomitus squalens, is crucial for advancing our knowledge of lignocellulose degradation. This study identifies D. squalens Bhr1 as a key regulator of (hemi-)cellulase production on mannose-rich substrates and further distinguishes basidiomycete transcription factors involved in plant biomass degradation from their ascomycete counterparts. Our findings highlight the significance of lineage-specific regulators in facilitating adaptive enzyme production for efficient biomass utilization, which is critical to carbon cycling in terrestrial ecosystems. This work establishes a foundation for exploring novel regulatory strategies among wood-degrading fungi, potentially enabling targeted strain engineering in biotechnological applications.

Mannose

Fungal and algal lichen symbionts show different transcriptional expression patterns in two climate zones.

In the lichen symbiosis, the fungal and algal partners constitute a closely integrated system. The combination of fungal and algal partners changes along climate gradients in many species, and is expected to be adaptive. However, the functional mechanisms behind this symbiosis-mediated environmental adaptation are unknown. We investigated which transcriptional profiles are associated with specific fungal-algal symbiont pairings found in lichens from high-elevation (Lower Supratemperate) and low-elevation (Lower Mesomediterranean) sites at two extremes of a climatic gradient on Mount Limbara, Sardinia. Using laboratory-acclimatized thalli, we found that lichen fungal and algal symbionts show variable expression profiles between high- and low-elevation individuals: circadian- and temperature-associated genes for fungi and light-responsive genes for algae show climate-specific patterns. High- and low-elevation individuals differentially express sugar transporters in both symbionts, pointing to symmetrical and climate-dependent sugar transport mechanisms between them. A light pulse treatment identified asymmetries between fungal and algal light responses, with high- and low-elevation fungal symbionts but only low-elevation algal symbionts showing a response. Together, these results tie previously observed genomic variation along climatic gradients in a lichen species to functional differences in transcription for the fungal and algal symbionts, contributing to our understanding of environmental specialization and niche-specific partner combinations in lichens.

Lichens

Trichoderma reesei Nsd3 transcription factor: pleiotropic roles in development, stress response, secondary metabolism, and cellulase production.

Trichoderma reesei is known for its ability to secrete high amounts of cellulases, enzymes of fundamental importance in generating products from lignocellulosic biomass. Diverse signaling pathways and transcription factors (TFs) control the cellulolytic repertoire in T. reesei to ensure correct adaptation to the environment. Here, we analyzed RNA-Seq data and identified a new potential regulator of cellulase production in T. reesei: a novel TF named Nsd3, a homolog of NsdC from Aspergilli. Deletion of nsd3 reduced vegetative growth and conidiation on solid medium. Phenotypic characterization of the Δnsd3 strain showed that it is more sensitive to osmotic stress, but more resistant to cell wall and oxidative stresses. Our results showed that Nsd3 is a repressor of cellulase expression by directly regulating key genes in the cellulolytic pathway, an unreported role for this TF in fungi. Loss of nsd3 leads to a faster and more robust induction of cellulolytic genes, and higher cellulase and hemicellulase activities. Transcriptional profiling by RNA-Seq, chromatin accessibility profiling by ATAC-Seq, and protein-DNA interaction assays showed that sugar transporters are important targets of Nsd3 during cellulase expression regulation. Combined with microscopy and gene expression analyses, the ATAC-Seq data also highlighted Nsd3 as a central regulator of cell wall remodeling and organization. Furthermore, the transcriptomics also showed that Nsd3 regulates genes involved in secondary metabolism. These results showed that Nsd3 regulates several physiological processes and provide novel insights into the regulatory system of cellulases in T. reesei that can be used in the design of high-performance strains for biorefinery.IMPORTANCETrichoderma reesei is a key player in the production of hydrolytic enzymes for the degradation of lignocellulose biomass, and transcription factors are important targets for genetic engineering to construct cellulase-hyperproducing strains. Here, we identified the transcription factor Nsd3 and characterized its role as a regulator of cellulase production in T. reesei. We applied two powerful genomics methods (transcriptome sequencing and chromatin accessibility sequencing) to unravel the global role of Nsd3 and its regulatory mechanism. Nsd3 participates in various biological processes in T. reesei, including cell wall remodeling, calcium metabolism, and secondary metabolism, in addition to regulating the expression of sugar transporters. Protein-DNA interaction assays demonstrate that Nsd3 acts through important genes to regulate cellulase expression, including ace4, crt1, stp1, and cel1b. Our study provides mechanistic insights about how Nsd3 regulates diverse physiological processes in T. reesei. This work also applied ATAC-Seq for the first time to study chromatin accessibility in T. reesei.

ATAC-Seq

Xy-31 and Lat-1 regulate the induction of polysaccharide disintegrating genes by arabinose in Neurospora crassa OR74A.

BACKGROUND: Arabinose has been identified as a potent inducer of the cellulase regulon in filamentous fungi. However, the precise molecular mechanisms that drive this induction remain largely unknown. This study aimed to elucidate the mechanisms underlying the arabinose-induced activation of cellulase and hemicellulase enzyme clusters in the model filamentous fungus Neurospora crassa OR74A. RESULTS: Arabinose stimulates the secretion of cellulases and hemicellulases in N. crassa. While genome-wide scrutiny predicted several sugar transporters in N. crassa, expression studies under avicel and arabinan conditions indicated a notable upregulation of pentose transporters encoded by the lat-1 and xy-31 genes. The lat-1 and xy-31 deleted strains showed reduced arabinose uptake and diminished growth on arabinose media, highlighting their role in arabinose transport. Additionally, these transporter-deficient strains exhibited a significant decrease in endoglucanase and arabinase activity, which correlated with lower expression of cellulase-encoding transcripts, indicating the crucial roles of Lat-1 and Xy-31 in promoting the secretion of enzymes that degrade biomass. Consistent with these findings, overexpression of lat-1 and xy-31 in N. crassa resulted in a significant increase in cellulase secretion. CONCLUSION: We demonstrated that N. crassa has multiple pentose transporters. Furthermore, we validated that the Lat-1 and Xy-31 transporters play crucial roles in arabinose-mediated induction of polysaccharide-disintegrating enzymes in N. crassa. Both transporters are required for efficient arabinose uptake and for the subsequent arabinose-dependent induction of polysaccharide-disintegrating enzymes. Collectively, these findings significantly advance the molecular understanding of fungal hemicellulose utilization and identify key transporters that represent promising targets for enhancing fungal biomass bioconversion.

arabinose

Cranberry juice potentiates sensitivity of uropathogenic Escherichia coli (UPEC) strains to fosfomycin and decreases occurrence of spontaneous resistance.

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTIs). The growing prevalence of antimicrobial resistance underscores the need for alternative or complementary strategies to enhance antibiotic activity. Fosfomycin (FOS) remains a recommended first-line treatment for uncomplicated UTIs due to its broad activity and low resistance rates; however, spontaneous resistance frequently arises through mutations in bacterial transport systems. Cranberry juice is known for its anti-adhesive and anti-infective properties; however, its potential to modulate antibiotic activity remains poorly understood. Here, we show that cranberry juice markedly potentiates the antibacterial activity of FOS and limits the emergence of resistance in UPEC clinical isolates. In 72% of the 32 tested isolates, cranberry juice significantly increased FOS inhibition activities and reduced spontaneous FOS-resistant mutant frequencies by up to five orders of magnitude. Whole-genome sequencing revealed distinct mutational patterns: FOS-resistant mutants selected without cranberry juice primarily carried glpT mutations, whereas those obtained with juice harbored mutations in uhpT or associated regulatory genes. Reporter assays indicated that cranberry juice represses glpT expression while maintaining UhpT-mediated FOS uptake, thereby sustaining antibiotic entry and activity. These results demonstrate that cranberry juice alters bacterial carbohydrate transport regulation to potentiate FOS activity and suppress resistance emergence. This study provides novel evidence that a natural product can enhance FOS activity, highlighting its potential as an antibiotic adjuvant for UTI management.IMPORTANCEAntimicrobial resistance is a growing threat to public health, and new strategies are needed to preserve the activity of existing antibiotics. This study reveals that cranberry juice, a widely consumed natural product, enhances the antibacterial activity of fosfomycin against uropathogenic Escherichia coli by modulating bacterial sugar transport systems. By shifting fosfomycin uptake from GlpT- to UhpT-mediated pathways, cranberry juice both potentiates antibiotic activity and suppresses the emergence of resistant mutants. These findings provide new insight into how dietary components can influence antibiotic response, offering a promising basis for developing natural adjuvants that extend the lifespan of current antimicrobial agents.

Fosfomycin

Integrative haplotype and SNP-based GWAS supports the identification of stable genomic loci controlling yield-related traits in soybean.

Soybean yield is vulnerable to environmental variation, therefore, it is important to detect and implement stable genomic regions associated with yield-related traits in soybean breeding programs. In this study, SNP and haplotype-based GWAS were conducted to reveal important candidate genomic regions and putative candidate genes associated with soybean yield-related traits. This study demonstrates that the integration of haplotype and SNP-based GWAS could improve the detection of genomic regions associated with complex traits, enhance statistical power, and facilitate the identification of biologically relevant candidate genes. Ten stable haplotype blocks and six stable SNPs were detected based on the integration of haplotype and SNP-based GWAS, respectively. Furthermore, multiple candidate genes associated with the yield-related traits were identified. For instance, six genes were identified as transporters, including Glyma.15G092800, encoding serine-type endopeptidase activity, Glyma.15G203300 encoding a major facilitator superfamily (MFS) sugar transporter, Glyma.04G163000, transmembrane transporter, and Glyma.04G164100, leucine-rich repeat receptor-like protein kinase (LRR-RLK), as the most promising candidate genes. Additionally, three genes involved in signaling and pathways of various phytohormones can be promising candidates for increasing seed yield through improving plant architecture in soybean plants. The identified superior haplotypes with favourable alleles will be useful for marker-assisted selection in future breeding programs in soybean.

DArT markers

The Streptococcus pyogenes mannose phosphotransferase system (Man-PTS) influences antimicrobial activity and niche-specific nasopharyngeal infection.

Streptococcus pyogenes is a human-adapted pathogen that can cause multiple diseases, including pharyngitis and skin infections. Although this bacterium produces many virulence factors, how S. pyogenes competes with the host microbiota is not well understood. Here, we detected antimicrobial activity from S. pyogenes MGAS8232 that prevented the growth of Micrococcus luteus. This activity was produced when cells were grown in 5% CO2 in M17 media supplemented with galactose; however, the addition of alternative sugars coupled with genome sequencing experiments revealed that the antimicrobial phenotype was not related to classical bacteriocins. To further determine genes involved in the production of this activity, a transposon mutant library in S. pyogenes MGAS8232 identified the mannose phosphotransferase system (Man-PTS), a major sugar transporter, as important for the antimicrobial phenotype. Loss-of-function transposon mutants linked to the antimicrobial activity were identified to also be involved in alternative sugar utilization, and additionally, the Man-PTS was further identified from an inadvertent secondary mutation in a bacteriocin operon mutant. Sugar utilization in the Man-PTS mutants demonstrated that galactose, mannose, and N-acetylglucosamine utilization was impaired. RNA-seq experiments in high and low glucose concentrations further characterized the Man-PTS as a glucose transporter; however, transcriptional regulators or virulence factors were not affected with the loss of the Man-PTS. Deletion of Man-PTS demonstrated defects in a mouse model of nasopharyngeal infection but not skin infection. This work suggests that the ability of S. pyogenes to utilize alternative sugars presented by glycans may play a role in acute infection and interactions with the endogenous microbial population existing in the nasopharynx.IMPORTANCEStreptococcus pyogenes is responsible for over 500,000 deaths per year primarily due to invasive infections and post-infection sequelae, although the most common manifestations include pharyngitis and impetigo. S. pyogenes can adapt to its environment through alternative sugar metabolism. Here, we identified an antimicrobial phenotype that was not bacteriocin-related but a by-product of alternative sugar metabolism. The mannose phosphotransferase system was involved in the production of the antimicrobial and was also important for S. pyogenes to utilize alternative sugars and establish nasopharyngeal infection but not skin infection. Overall, this study identified potential strategies used by S. pyogenes for interactions with the endogenous microbiota and further elucidated the importance of sugar metabolism in acute upper respiratory tract infection.

Streptococcus pyogenes

Co-option of stomata in the convergent evolution of fern nectaries.

Understanding the origin of new structures is a central goal of evolutionary biology. In many instances, novel phenotypes arise through heterotopy: the expression of a structure in a new location. Using bracken fern (Pteridium aquilinum) as a model, we combine genomics, transcriptomics and metabolomics to begin to explore the origin and developmental routes in the convergent evolution of ant-enticing nectaries. We observe that P. aquilinum does not exclusively express flowering plant 'nectary genes' during nectary development. Rather, this fern builds nectaries through co-option of stomata. Specifically, P. aquilinum heterotopically expresses canonical angiosperm stomatal regulatory genes, leading to stomatal development in novel positions along the petiole. These non-laminar stomata were co-opted for nectar secretion through the expression of putative sugar transport genes, forming secretory nectarostomata. This work provides two advances in our understanding of nectary evolution and the origin of complex structures. First, heterotopic expression of stomata, and later exaptation, represents one realized developmental mechanism for the evolution of nectar glands. Second, while there are many routes to nectary evolution, nectarostomata development is a repeatable path that has evolved in ferns and flowering plants, representing an impressive case of convergent evolution through the same developmental mechanism, despite over 400 million years of divergent history.

Plant Stomata

Tonoplast sucrose transporter SUT4-dependent sugar partitioning modulates phenological transitions and reproductive success in poplar.

Climate uncertainty is intensifying the need for greater plasticity in carbohydrate reserve utilization to support winter survival and spring growth in woody perennials. In poplar, the single-copy SUT4, which encodes a tonoplast-localized sucrose transporter, and the SUT5/SUT6 genome duplicates, which encode plasma membrane-localized transporters, are expressed year-round, with SUT4 showing the highest expression during cool seasons. Given its role in vacuolar sucrose efflux and winter-predominant expression, SUT4 may play a key role in modulating seasonal carbohydrate dynamics. While SUT4-knockdown and knockout effects have been studied under greenhouse conditions, their impact under field conditions remains unexplored. Here, we report a field-based study comparing CRISPR knockout mutants of winter-expressed SUT4 and SUT5/SUT6 in Populus tremula × alba. We show that sut4, but not sut5/6, mutants exhibited earlier autumn leaf senescence, delayed spring bud flush, reduced stem growth, and altered sugar partitioning in winter xylem and bark relative to controls. After 2 years in the field, all genotypes flowered before leaf flush in early spring; however, sut4 mutants produced sterile ovules despite developing normal-looking catkins. Metabolic profiling revealed disrupted sucrose and raffinose dynamics in elongating sut4 catkins. This was accompanied by transcriptomic signatures of elevated stress and downregulation of proanthocyanidin biosynthesis and circadian clock genes. These findings highlight the critical role of SUT4 in coordinating sugar allocation, stress responses, and seasonal development in poplar.

Populus

SLC35G3 is a UDP-N-acetylglucosamine transporter for sperm glycoprotein formation and underpins male fertility in mice.

Despite the recognized importance of glycans in biological phenomena, their complex roles in spermatogenesis and sperm function remain unclear. SLC35G3, a 10-transmembrane protein specifically found in early round spermatids, belongs to the sugar-nucleotide transporter family, indicating its involvement in glycan formation. In this study, we found that Slc35g3 knockout male mice were sterile due to impaired sperm functions in uterotubal junction passage, zona pellucida binding, and oocyte fusion. Mouse SLC35G3 has UDP-GlcNAc transporter activity, and its ablation caused abnormal processing of the sperm plasma membrane and acrosome membrane proteins. Reported human SLC35G3 mutations (F267L and T179HfsTer27) diminished the UDP-GlcNAc transporter activity of SLC35G3, implying infertility risks in males carrying these mutations. Our findings unveil the vital roles of SLC35G3 in the glycan formation of sperm membrane proteins critical for sperm fertilizing ability.

Biological Sciences

Mechanistic roles of GmSWEET10a/b and GmSUT1 in the oil-protein balance in soybean mature seeds at transcriptional and metabolic levels.

Previous investigations indicated that the soybean (Glycine max) SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER10a/b (GmSWEET10a/b) genes promote oil accumulation, while inhibiting protein accumulation in seeds. To clarify the mechanisms modulated by GmSWEET10a/b in mediating the oil and protein accumulations in soybean seeds, an integrated comparative multiomics was conducted using the double gmsweet10a,b mutant and wild-type (WT) embryos. Spatial metabolomic analysis revealed that gmsweet10a,b embryos were surrounded by a sugar-reduced seed coat and experienced a sugar-starvation state in embryonic tissues in vivo. The decreased sugar content in the gmsweet10a,b embryos reduced the availability of carbon skeletons required for oil synthesis and was associated with decreased expression levels of genes involved in sucrose metabolism, fatty acid biosynthesis, and triacylglycerol assembly. Meanwhile, the expression of genes encoding storage protein was induced in gmsweet10a,b embryos, when compared with WT. These changes resulted in decreased oil content and increased protein content in gmsweet10a,b embryos versus WT. In vitro sugar-starvation assay also supported the suppression of fatty acid biosynthesis and the enhanced storage protein accumulation in developmental embryo under sugar-starved conditions. Furthermore, the knockout of SUCROSE TRANSPORTER 1 (GmSUT1), which was upregulated in gmsweet10a,b embryos, significantly decreased the sugar level, resulting in lower oil content but higher protein content in gmsut1 embryos than WT ones. Our findings provided a mechanistic understanding of the modulation of sugar transport between seed coat to embryo by both GmSWEET10a/b and GmSUT1, which plays a pivotal role in balancing oil and protein accumulations in soybean mature seeds.

Seeds

Cellodextrin Metabolism and Phosphotransferase System-Catalyzed Uptake in Enterococcus faecalis.

Two PTS transporters involved in the uptake of cellobiose and short cellooligosaccharides were identified in Enterococcus faecalis. Genes coding for the different EII proteins are found in a locus composed of three operonic structures expressing two distinct EIIC (CelC1 and CelC2), two identical EIIB (CelB1 and CelB2) and a unique EIIA (CelA1). The EIIA plays a central role in β-glucoside uptake because it is required not only for β-homodiholosides but also for the diheteroside N-acetylglucosamine-L-asparagine. Depending on their size, cellooligosaccharides are preferably transported either by CelC1 (di-saccharides) or by CelC2 (4 glycosidic residues and more), with tri-saccharides being taken up by both EIIC transporters. Moreover, CelA1B2C2 require CelGHI to be functional, three small proteins, the function of which remains unknown. CelA1B1C1 is the main but not exclusive transporter of cellobiose and chitobiose. It is involved in the transport of other β-glucodisaccharides, such as laminaribiose and sophorose. This PTS can be complemented by other transporters highlighting the existence of a network for β-glucoside uptake. This locus is under the control of CelR, a LevR-like transcription activator.

Enterococcus faecalis

The TANG cluster comprising ten nitrate transporter genes controls fruit sweetness and size in tomato.

Sucrose is a major transport form of photoassimilated carbon in tomato, Arabidopsis, and many other plant species, and plays a critical regulatory role in plant growth, development, and fruit quality. Plant vacuoles function as storage organelles, accumulating substantial quantities of metabolically inactive nitrates as a nitrogen reserve and soluble sugars as a carbon reserve. Consequently, the balance between nitrate and sucrose accumulation determines plant growth dynamics and fruit taste. In this study, we identified a gene cluster designated TANG (Total soluble solidsAccumulation viaNitrate transporterGene cluster), comprising ten nitrate transporter genes that are significantly associated with sucrose accumulation in tomato. This gene cluster mediates the transport of nitrate between the cytoplasm and vacuole, thereby influencing its storage. Functional disruption of TANG8, a member of the gene cluster, results in either enhanced sugar accumulation or increased fruit size. Selective disruption of multiple TANG cluster members yields fruits with elevated sweetness and increased fruit size in S. pimpinellifolium. The interaction between the TANG members and a tonoplast localized Sucrose Transporter 4 provides insight into the competitive accumulation of nitrate and sugar. The multiplex editing of a gene cluster provides a successful example of engineering crops with high quality and yield.

Gene cluster

Two-Step Loss of GLUTs in the High-Metabolism Passerines.

Glucose transporters (GLUTs) play vital roles in cellular metabolism. Understanding their evolutionary dynamics in birds is essential for elucidating avian physiology and adaptation. However, the choice of gene detection method in gene family analysis may affect the conclusion. Here, we present a comprehensive investigation of methodologies and GLUT gene loss events in avian lineages, focusing on the loss of GLUT4 and GLUT8. To illustrate the effects of these methods, we first employed BUSCO-based homolog identification, calculated pairwise evolutionary distances between different species, and performed separate blastn and blastp searches to identify homologs in two groups of animals. Our analyses revealed a significant decline in blastn accuracy with increasing evolutionary distance, represented by relative divergence times. Through a more robust blastp-based gene detection pipeline, we provide evidence for the loss of GLUT genes in birds based on 58 vertebrate genomes, including 47 bird species. Our results support the reported early loss of GLUT4 in Aves. We also newly emphasize the absence of GLUT8 in passerines, potentially due to adaptation to high-sugar diets in their ancestors. These findings enhance our knowledge of avian metabolism and the evolution of GLUT genes.

Animals

Physiological and metabolic responses of Zymomonas mobilis to lignocellulosic hydrolysate.

Zymomonas mobilis is a promising biocatalyst for the sustainable conversion of lignocellulosic sugars into biofuels and bioproducts, yet its response to lignocellulosic hydrolysates remains poorly understood. Here, we investigate the physiological response of Z. mobilis to ammonia fiber expansion (AFEX)-pretreated switchgrass hydrolysate using a systems-level approach integrating LC-MS/MS-based lipidomics and shotgun proteomics. Growth on hydrolysate induced substantial shifts in fatty acid and membrane phospholipid composition, alongside broad proteomic remodeling. Notably, Z. mobilis exhibited a stress response characterized by the upregulation of heat shock proteins and efflux transporters and the downregulation of cell motility proteins. Unexpectedly, hydrolysate exposure also led to a robust upregulation of the Entner-Doudoroff pathway, the ethanol fermentation pathway, and other central carbon metabolism enzymes, indicating a substantial cellular investment potentially driven by additional nutrient availability in hydrolysate. These findings provide new insights into the metabolic adaptations of Z. mobilis to lignocellulosic hydrolysates, informing strategies to enhance its biofuel production capabilities.IMPORTANCEBiomass pretreatment processes release fermentable sugars from lignocellulosic biomass, but they also generate inhibitors that can impact microbial metabolism. This study provides a systems-level evaluation of how Zymomonas mobilis responds to hydrolysate stress, revealing distinct physiological and lipid membrane remodeling responses. While some stress responses overlap with those induced by ethanol and isobutanol toxicity, both valuable biofuels, hydrolysate exposure elicits unique metabolic shifts. These findings offer valuable insights for engineering Z. mobilis strains with improved tolerance and performance for efficient bioconversion of lignocellulosic hydrolysates into biofuels and bioproducts.

Zymomonas