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At least 289 records · Page 16Linked to original sources
PubMed1995

Decreased mitochondrial biogenesis in temperature-sensitive cell division cycle mutants of Saccharomyces cerevisiae.

The temperature-sensitive cell division cycle (cdc) G1 mutants cdc28 and cdc35 show decreased mitochondrial volumes with respect to the wild type strain A364A (WT) at the restrictive temperature. Of the three criteria of mitochondrial biogenesis studied, that is, number of mitochondria per cell, relative area of the cell occupied by mitochondria, or relative area of mitochondria occupied by inner membranes, only the second indicator was significantly lower in cdc mutants than in the WT. The mitochondrial inner membranes development did not compensate for the decrease in the organelles volume. Apparently, the reduced mitochondrial biogenesis was not due to the temperature shift because the relative area of the cell occupied by mitochondria was already significantly lower at 25 degrees C in cdc mutants. The specific fluxes of oxygen consumption confirmed that the respiratory capacity of cdc mutants is largely impaired in respect to the WT. Cdc28 and cdc35 mutants of Saccharomyces cerevisiae had been previously shown to exhibit high respiratory quotients (from 3 to 7) in respect to the WT (RQ approximately 1.0), which correlated with carbon and energy uncoupling probably the result of glucose-induced catabolite repression [Aon MA, Mónaco ME, Cortassa S (1995) Exp Cell Res 217, 42-51; Mónaco ME, Valdecantos PA, Aon MA (1995) Exp Cell Res 217, 52-56].

G1 Phase↗
PubMed1995

The cycHJKL gene cluster plays an essential role in the biogenesis of c-type cytochromes in Bradyrhizobium japonicum.

We present an extended genetic analysis of the previously identified cycH locus in Bradyrhizobium japonicum. Three new open reading frames found in an operon-like structure immediately adjacent to the 3' end of cycH were termed cycJ, cycK and cycL. A deletion mutant (delta cycHJKL) and biochemical analysis of its phenotype showed that the genes of the cluster are essential for the biogenesis of cellular c-type cytochromes. Mutations in discrete regions of each of the genes were also constructed and shown to affect anaerobic respiration with nitrate and the ability to elicit an effective symbiosis with soybean, both phenotypes being a consequence of defects in cytochrome c formation. The CycK and CycL proteins share up to 53% identity in amino acid sequence with the Rhodobacter capsulatus Cc11 and Cc12 proteins, respectively, which have been shown previously to be essential for cytochrome c biogenesis, whereas cycJ codes for a novel protein of 169 amino acids with an M(r) of 17857. Localisation studies revealed that CycJ is located in the periplasmic space; it is probably anchored to the cytoplasmic membrane via an N-terminal hydrophobic domain. Based on several considerations discussed here, we suggest that the proteins encoded by the cycHJKL-cluster may be part of a cytochrome c-haem lyase complex whose active site faces the periplasm.

Amino Acid Sequence↗
PubMedDate not supplied

Physical foundations of the probability of biogenesis.

For bigenesis-a particular kind of systmogenesis-to occur, certain physical and informative requirements were indispensable, especially: (1) the selforganization of new kind of negative feed-backs supported by the trans-substantial channels of information. These were certainly at first organized only on the submolecular level, each of them consisting of many charge-transfer connections. The accomplishment of requirement (1) depends on (2) and (3): (2) the organization of a sufficiently complex structure inside the agglomerated system. We should mention here the desagglomerated inorganic systems according to the archaic models: 'A' (Atoms) and P (astro-Planetary systems). In these prebiotic models the selfregulation background consists of the kind of negative opposing forces). (3) the availability of molecules in which the structure complexity is sufficiently high to be able to contribute to the organization of the trans-substantial channels. Biogenesis of spontaneous trans-substantialization of information channels in feed-backs. The trans-substantial channels are spontaneously organized in the biotic model, but they are also present in many technical electronic models of systems constructed by man. Therefore, it is no wonder that biogenesis probably occurred at the 10--6 m size level (compare the diameter of the microspheres of Fox and the concept of Ponnamperuma who mentions the size of the contemporary Micrococcus). Such a system position - inside the biotic unicellular sub-band (extended actually from 10--6 to 10--1 m) is faviourable for the organization of the high complexity of the structurogenic processes trajectories. It is at the nearest possible level to this region on the dimensional scale where a maximal plurality of the different joining forces exists...

Biological Evolution↗
PubMed1994

The receptor-recycling and lysosome biogenesis mutant TfT1.11 belongs to a new complementation group, End6.

We have previously isolated a Chinese hamster ovary (CHO) mutant with a temperature-dependent pleiotropic defect in receptor recycling. This mutant, TfT1.11, has also been shown to have defects in fluid-phase endocytosis and lysosome biogenesis. Previously isolated CHO cell mutants with defects in endocytosis have been assigned to five recessive complementation groups (End1-End5). We have performed complementation analysis using polyethylene glycol-induced fusion of genetically marked sublines of TfT1.11 with representative mutants from each of the End groups. Complementation of the receptor trapping and lysosome biogenesis defects as well as temperature lethality was observed with all groups, demonstrating that TfT1.11 defines a new complementation group, End6.

Animals↗
PubMed1984

Papulacandin B: inhibitor of biogenesis of (1----3)-beta-D-glucan fibrillar component of the cell wall of Saccharomyces cerevisiae protoplasts.

The effect of papulacandin B on regenerating protoplasts of Saccharomyces cerevisiae was studied by light and electron microscopy. In liquid media it inhibited the biogenesis of (1----3)-beta-D-glucan fibrillar nets; as a result, the protoplasts did not grow polarly but only spherically. The effect was reversible. Instead of the nets the inhibited protoplasts synthesized only individual microfibrils soluble in hydroxide; these were not joined in the nets and were partially masked by amorphous material. The microfibrils disintegrated after lysis and did not maintain the shape of protoplasts. Protoplasts inhibited in solid media grew spherically up to 25 micron but they did not divide or revert, in spite of forming cell walls. These walls were amorphous and fragile and they disintegrated during preparation. Papulacandin B did not decrease the viability of protoplasts and did not interfere with their growth, biogenesis of alkali-soluble glucan microfibrils or amorphous wall matrix. It inhibited specifically the synthesis of alkali-insoluble branched (1----3)-beta-D-glucan, a necessary building unit required for the formation of the fibrillar component of the cell wall responsible for the cell wall shape, its rigidity and tensile strength.

Aminoglycosides↗
PubMed2001

Molecular biology of chloroplast biogenesis: gene expression, protein import and intraorganellar sorting.

The chloroplast is the hallmark organelle of plants. It performs photosynthesis and is therefore required for photoautotrophic plant growth. The chloroplast is the most prominent member of a family of related organelles termed plastids which are ubiquitous in plant cells. Biogenesis of the chloroplast from undifferentiated proplastids is induced by light. The generally accepted endosymbiont hypothesis states that chloroplasts have arisen from an internalized cyanobacterial ancestor. Although chloroplasts have maintained remnants of the ancestral genome (plastome), the vast majority of the genes encoding chloroplast proteins have been transferred to the nucleus. This poses two major challenges to the plant cell during chloroplast biogenesis: First, light and developmental signals must be interpreted to coordinately express genetic information contained in two distinct compartments. This is to ensure supply and stoichiometry of abundant chloroplast components. Second, developing chloroplasts must efficiently import nuclear encoded and cytosolically synthesized proteins. A subset of proteins, including such encoded by the plastome, must further be sorted to the thylakoid compartments for assembly into the photosynthetic apparatus.

Biological Transport↗
PubMed2007

A housekeeper with power of attorney: the rRNA genes in ribosome biogenesis.

Ribosome biogenesis centres both physically and functionally on the activity of the ribosomal RNA (rRNA) genes. Ribosome assembly occurs co-transcriptionally on these genes, requires the coordinated expression and assembly of many hundreds of proteins and is finely tuned to cell and organism growth. This review presents contemporary understanding of the mode and the means of rRNA gene transcription and how growth factors, oncogenes and tumour suppressors regulate this transcription. It is argued that transcription elongation is a key mechanism regulating rRNA gene transcription. This unorthodox view provides a logical framework to explain the co-transcriptional phase of ribosome biogenesis.

Animals↗
PubMed2005

Polyunsaturated fatty acids of marine origin upregulate mitochondrial biogenesis and induce beta-oxidation in white fat.

AIMS/HYPOTHESIS: Intake of n-3 polyunsaturated fatty acids reduces adipose tissue mass, preferentially in the abdomen. The more pronounced effect of marine-derived eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids on adiposity, compared with their precursor alpha-linolenic acid, may be mediated by changes in gene expression and metabolism in white fat. METHODS: The effects of EPA/DHA concentrate (6% EPA, 51% DHA) admixed to form two types of high-fat diet were studied in C57BL/6J mice. Oligonucleotide microarrays, cDNA PCR subtraction and quantitative real-time RT-PCR were used to characterise gene expression. Mitochondrial proteins were quantified using immunoblots. Fatty acid oxidation and synthesis were measured in adipose tissue fragments. RESULTS: Expression screens revealed upregulation of genes for mitochondrial proteins, predominantly in epididymal fat when EPA/DHA concentrate was admixed to a semisynthetic high-fat diet rich in alpha-linolenic acid. This was associated with a three-fold stimulation of the expression of genes encoding regulatory factors for mitochondrial biogenesis and oxidative metabolism (peroxisome proliferator-activated receptor gamma coactivator 1 alpha [Ppargc1a, also known as Pgc1alpha] and nuclear respiratory factor-1 [Nrf1] respectively). Expression of genes for carnitine palmitoyltransferase 1A and fatty acid oxidation was increased in epididymal but not subcutaneous fat. In the former depot, lipogenesis was depressed. Similar changes in adipose gene expression were detected after replacement of as little as 15% of lipids in the composite high-fat diet with EPA/DHA concentrate, while the development of obesity was reduced. The expression of Ppargc1a and Nrf1 was also stimulated by n-3 polyunsaturated fatty acids in 3T3-L1 cells. CONCLUSIONS/INTERPRETATION: The anti-adipogenic effect of EPA/DHA may involve a metabolic switch in adipocytes that includes enhancement of beta-oxidation and upregulation of mitochondrial biogenesis.

Adipocytes↗
PubMed2004

Biogenesis of CFTR and other polytopic membrane proteins: new roles for the ribosome-translocon complex.

Polytopic protein biogenesis represents a critical, yet poorly understood area of modern biology with important implications for human disease. Inherited mutations in a growing array of membrane proteins frequently lead to improper folding and/or trafficking. The cystic fibrosis transmembrane conductance regulator (CFTR) is a primary example in which point mutations disrupt CFTR folding and lead to rapid degradation in the endoplasmic reticulum (ER). It has been difficult, however, to discern the mechanistic principles of such disorders, in part, because membrane protein folding takes place coincident with translation and within a highly specialized environment formed by the ribosome, Sec61 translocon, and the ER membrane. This ribosome-translocon complex (RTC) coordinates the synthesis, folding, orientation and integration of transmembrane segments across and into the ER membrane. At the same time, RTC function is controlled by specific sequence determinants within the nascent polypeptide. Recent studies of CFTR and other native membrane proteins have begun to define novel variations in translocation pathways and to elucidate the specific steps that establish complex topology. This article will attempt to reconcile advances in our understanding of protein biogenesis with emerging models of RTC function. In particular, it will emphasize how information within the nascent polypeptide is interpreted by and in turn controls RTC dynamics to generate the broad structural and functional diversity observed for naturally occurring membrane proteins.

Animals↗
PubMed2000

Isolation of Penicillium chrysogenum PEX1 and PEX6 encoding AAA proteins involved in peroxisome biogenesis.

In Penicillium chrysogenum, key enzymes involved in the production of penicillin reside in peroxisomes. As a first step to understand the role of these organelles in penicillin biosynthesis, we set out to isolate the genes involved in peroxisome biogenesis. Here we report the cloning and characterization of P. chrysogenum PEX1 and PEX6, which encode proteins of the AAA family of ATPases. The second AAA module, which is essential for the function of Pex1p and Pex6p in peroxisome biogenesis, is highly conserved in both PcPexlp and PcPex6p. PcPEX1 and PcPEX6 contain three and two introns, respectively.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2002

Nep1p (Emg1p), a novel protein conserved in eukaryotes and archaea, is involved in ribosome biogenesis.

The essential Saccharomyces cerevisiae gene YLR186w [ NEP1 (nucleolar essential protein 1), also recently named EMG1 (essential for mitotic growth 1)] is highly conserved in eukaryotes and archaea. In S. cerevisiae, Nep1p is localized in the nucleus with a rod-shaped morphology, which first suggested a spindle/microtubule association for ScNEP1 (S. cerevisiae NEP1). However, in Candida albicans and in HeLa cells, Nep1p is a protein of the nucleoli. CaNEP1 (C. albicans NEP1) and HsNEP1 (Homo sapiens NEP1) heterologously complement the essential phenotype in a S. cerevisiae nep1 deletion mutant. However, the ScNEP1 spindle/microtubule phenotype is not found with HsNEP1 and CaNEP1, which shows that the spindle/microtubule association is specific for ScNep1p and that it is not the primary essential function of Nep1p. A temperature-sensitive ScNEP1 (ts1) allele was isolated and revealed a strongly increased sensitivity to paromomycin, a translational inhibitor which binds to RNA, indicating that ribosome biogenesis within the nucleolus is probably affected. This was confirmed by polysome profile and ribosomal subunit analysis, showing a ribosomal subunit imbalance with a decrease in 40S subunits, due to reduced amounts of native 18S rRNA. Furthermore, ScSAM2, encoding S-adenosylmethionine synthetase, was isolated as a multicopy-suppressor of the ScNEP1 (ts1) mutant allele and medium supplementation with S-adenosylmethionine restored its growth. For the first time, these results identified a novel protein with an essential function in ribosomal biogenesis which directly or indirectly interferes with a methylation reaction during the early steps of pre-rRNA processing necessary for the generation of 40S ribosomal subunits.

Amino Acid Sequence↗
PubMed2003

Role for lipid signaling and the cell integrity MAP kinase cascade in yeast septum biogenesis.

Polarized deposition of chitin at the bud neck is essential for cell separation in yeast. Chitin septum biogenesis is catalyzed by two distinct chitin synthase activities encoded by the CHS2 and CHS3 genes. The phosphoinositide phosphatase Sac1p is required for proper trafficking of the Chs3p chitin synthase. sac1 mutants also display a severe synthetic growth defect, with mutations in the SLT2 gene which encodes a MAP kinase involved in cell integrity. We characterized the defect that underlies this genetic interaction and found that sac1 Delta slt2 Delta cells arrest as large-budded cells because they fail to separate at the end of mitosis. This inability to complete cell division appears to be caused by an increased deposition of chitin at the septum area and correlates with a mislocalized accumulation of the Chs2p chitin synthase at the cell periphery. Our data therefore indicate that Sac1p and Slt2p have synergistic roles in regulating chitin septum biogenesis.

Catalysis↗
PubMed1996

The role of protein degradation in mitochondrial function and biogenesis.

It has been known for a long time that mitochondria contain their own protein-degradation systems. Only recently, however, have genes for mitochondrial proteases been identified and the powerful techniques of molecular biology been applied to gain insight into the role of protein degradation in mitochondrial biogenesis. It is now clear that the mitochondrial proteases that are involved in the initial stages of degradation are similar to prokaryotic ATP-dependent proteases, and that a division of labour exists between soluble and membrane-bound systems. These systems are essential for the biogenesis of fully functional mitochondria. Their natural targets are currently being identified, and their co-operation with chaperones and possible dual functions as chaperones/proteases are being investigated.

Adenosine Triphosphate↗
PubMed2000

Cell cycle maintenance and biogenesis of the Golgi complex.

How organelle identity is established and maintained, and how organelles divide and partition between daughter cells, are central questions of organelle biology. For the membrane-bound organelles of the secretory and endocytic pathways [including the endoplasmic reticulum (ER), Golgi complex, lysosomes, and endosomes], answering these questions has proved difficult because these organelles undergo continuous exchange of material. As a result, many "resident" proteins are not localized to a single site, organelle boundaries overlap, and when interorganellar membrane flow is interrupted, organelle structure is altered. The existence and identity of these organelles, therefore, appears to be a product of the dynamic processes of membrane trafficking and sorting. This is particularly true for the Golgi complex, which resides and functions at the crossroads of the secretory pathway. The Golgi receives newly synthesized proteins from the ER, covalently modifies them, and then distributes them to various final destinations within the cell. In addition, the Golgi recycles selected components back to the ER. These activities result from the Golgi's distinctive membranes, which are organized as polarized stacks (cis to trans) of flattened cisternae surrounded by tubules and vesicles. Golgi membranes are highly dynamic despite their characteristic organization and morphology, undergoing rapid disassembly and reassembly during mitosis and in response to perturbations in membrane trafficking pathways. How Golgi membranes fragment and disperse under these conditions is only beginning to be clarified, but is central to understanding the mechanism(s) underlying Golgi identity and biogenesis. Recent work, discussed in this review, suggests that membrane recycling pathways operating between the Golgi and ER play an indispensable role in Golgi maintenance and biogenesis, with the Golgi dispersing and reforming through the intermediary of the ER both in mitosis and in interphase when membrane cycling pathways are disrupted.

Animals↗
PubMed2001

The chaperonin GroEL and other heat-shock proteins, besides DnaK, participate in ribosome biogenesis in Escherichia coli.

It has been shown that in Escherichia coli the chaperone DnaK is necessary for the late stages of 50S and 30S ribosomal subunit assembly in vivo. Here we focus on the roles of other HSPs (heat-shock proteins), including the chaperonin GroEL, in addition to DnaK, in ribosome biogenesis at high temperature. GroEL is shown to be required for the very late 45S-->50S step in the biogenesis of the large ribosome subunit, but not for 30S assembly. Interestingly, overproduction of GroES/GroEL can partially compensate for a lack of DnaK/DnaJ at 44 degrees C.

Alleles↗
PubMed2001

Ria1p (Ynl163c), a protein similar to elongation factors 2, is involved in the biogenesis of the 60S subunit of the ribosome in Saccharomyces cerevisiae.

RIA1 (YNL163c) is a quasi-essential gene that encodes a protein with strong similarities to elongation factors 2. Small C-terminal deletions in the protein lead to a severe growth defect. In the case of a 22-residue C-terminal deletion this can be suppressed by intragenic mutations in the RIA1 gene or dominant extragenic mutations in TIF6, which is thought to be involved in the biogenesis of the 60S subunit of the ribosome. The dominant TIF6 alleles can also suppress the phenotype associated with a complete deletion of the RIA1 gene. Depletion of Ria1p has a dramatic effect on the polysome profile: there is a severe reduction in the level of the 80S monosomes, an imbalance in the 40S/60S ratio, and halfmers appear. Dissociation of the monosomes and polysomes in the Ria1p depletion mutant revealed a specific reduction in the amount of 60S subunits. Localization experiments with HA-tagged derivatives of Ria1p did not detect any stable association of Ria1p with ribosome subunits, 80S monosomes or polysomes. Cell fractionation experiments show that Ria1p is found in both the cytoplasmic fraction and the nuclear fraction. Taken together, these data suggest that Ria1p is involved in the biogenesis of the 60S subunit of the ribosome.

Cloning, Organism↗
PubMed2005

Role of microtubule-dependent membrane trafficking in acrosomal biogenesis.

The role of microtubule-based trafficking in acrosomal biogenesis was examined by studying the effects of colchicine on spermiogenesis. In electron micrographs of untreated cap-phase mouse spermatids, coated vesicles were always seen on the apex and caudal margins of the developing acrosomal cap. The increase in volume and the accumulation of materials in the acrosome during the Golgi and cap phases were observed to occur via fusion of vesicles at various sites on the growing acrosome. By studying the acid phosphatase localization pattern and colchicine-treated spermatids, the role of clathrin-coated vesicles became clear. Coated vesicle formation at the caudal margin of the acrosome appeared to be responsible for the spreading and shaping of the acrosome over the surface of the nucleus and also established distinct regional differences in the acrosome. In colchicine-treated spermatids, the Golgi apparatus lost its typical membranous stack conformation and disintegrated into many small vesicles. Acrosome formation was retarded, and there was discordance of the spread of the acrosomal cap with that of the modified nuclear envelope. Many symplasts were also found because of the breakdown of intercellular bridges. Colchicine treatment thus indicated that microtubule-dependent trafficking of transport vesicles between the Golgi apparatus and the acrosome plays a vital role in acrosomal biogenesis. In addition, both anterograde and retrograde vesicle trafficking are extensively involved and seem to be equally important in acrosome formation.

Acid Phosphatase↗
PubMed2007

Metabolic regulation of citrate and iron by aconitases: role of iron-sulfur cluster biogenesis.

Iron and citrate are essential for the metabolism of most organisms, and regulation of iron and citrate biology at both the cellular and systemic levels is critical for normal physiology and survival. Mitochondrial and cytosolic aconitases catalyze the interconversion of citrate and isocitrate, and aconitase activities are affected by iron levels, oxidative stress and by the status of the Fe-S cluster biogenesis apparatus. Assembly and disassembly of Fe-S clusters is a key process not only in regulating the enzymatic activity of mitochondrial aconitase in the citric acid cycle, but also in controlling the iron sensing and RNA binding activities of cytosolic aconitase (also known as iron regulatory protein IRP1). This review discusses the central role of aconitases in intermediary metabolism and explores how iron homeostasis and Fe-S cluster biogenesis regulate the Fe-S cluster switch and modulate intracellular citrate flux.

Aconitate Hydratase↗