Similar Datasets
Project description:During eukaryotic ribosome biogenesis, members of the conserved atypical serine/threonine protein kinase family, the RIO kinases (Rio1, Rio2 and Rio3) function in small ribosomal subunit biogenesis. Structural analysis of Rio2 indicated a role as a conformation-sensing ATPase rather than a kinase to regulate its dynamic association with the pre-40S subunit. However, it remained elusive at which step and by which mechanism the other RIO kinase members act. Here, we have determined the crystal structure of the human Rio1-ATP-Mg(2+) complex carrying a phosphoaspartate in the active site indicative of ATPase activity. Structure-based mutations in yeast showed that Rio1's catalytic activity regulates its pre-40S association. Furthermore, we provide evidence that Rio1 associates with a very late pre-40S via its conserved C-terminal domain. Moreover, a rio1 dominant-negative mutant defective in ATP hydrolysis induced trapping of late biogenesis factors in pre-ribosomal particles, which turned out not to be pre-40S but 80S-like ribosomes. Thus, the RIO kinase fold generates a versatile ATPase enzyme, which in the case of Rio1 is activated following the Rio2 step to regulate one of the final 40S maturation events, at which time the 60S subunit is recruited for final quality control check.
| S-EPMC4117770 | biostudies-literature
Project description:The atypical kinase Rio1 is widespread in many organisms, ranging from Archaebacteria to humans, and is an essential factor in ribosome biogenesis. Little is known about the protein substrates of the enzyme and small-molecule inhibitors of the kinase. Protein kinase CK2 was the first interaction partner of Rio1, identified in yeast cells. The enzyme from various sources undergoes CK2-mediated phosphorylation at several sites and this modification regulates the activity of Rio1. The aim of this review is to present studies of the relationship between the two different kinases, with respect to CK2-mediated phosphorylation of Rio1, regulation of Rio1 activity, and similar susceptibility of the kinases to benzimidazole inhibitors.
| S-EPMC5374425 | biostudies-literature
Project description:Deposition of additional plasma membrane and cargoes during cytokinesis in eukaryotic cells must be coordinated with actomyosin ring contraction, plasma membrane ingression and extracellular matrix remodelling. The process by which the secretory pathway promotes specific incorporation of key factors into the cytokinetic machinery is poorly understood. Here, we show that cell polarity protein Spa2 interacts with actomyosin ring components during cytokinesis. Spa2 directly binds to cytokinetic factors Cyk3 and Hof1. The lethal effects of deleting the SPA2 gene in the absence of either Cyk3 or Hof1 can be suppressed by expression of the hypermorphic allele of the essential chitin synthase II (Chs2), a transmembrane protein transported on secretory vesicles that makes the primary septum during cytokinesis. Spa2 also interacts directly with the chitin synthase Chs2. Interestingly, artificial incorporation of Chs2 into the cytokinetic machinery allows the localisation of Spa2 at the site of division. In addition, increased Spa2 protein levels promote Chs2 incorporation at the site of division and primary septum formation. Our data indicate that Spa2 is recruited to the cleavage site to co-operate with the secretory vesicle system and particular actomyosin ring components to promote the incorporation of Chs2 into the so-called 'ingression progression complexes' during cytokinesis in budding yeast.
| S-EPMC5895073 | biostudies-literature
Project description:Coupling cell cycle with nutrient availability is a crucial process for all living cells. But how bacteria control cell division according to metabolic supplies remains poorly understood. Here, we describe a molecular mechanism that coordinates central metabolism with cell division in the α-proteobacterium Caulobacter crescentus. This mechanism involves the NAD-dependent glutamate dehydrogenase GdhZ and the oxidoreductase-like KidO. While enzymatically active GdhZ directly interferes with FtsZ polymerization by stimulating its GTPase activity, KidO bound to NADH destabilizes lateral interactions between FtsZ protofilaments. Both GdhZ and KidO share the same regulatory network to concomitantly stimulate the rapid disassembly of the Z-ring, necessary for the subsequent release of progeny cells. Thus, this mechanism illustrates how proteins initially dedicated to metabolism coordinate cell cycle progression with nutrient availability.
| S-EPMC4516431 | biostudies-literature
Project description:EpsE is an ATPase that powers transport of cholera toxin and hydrolytic enzymes through the Type II secretion (T2S) apparatus in the gram-negative bacterium, Vibrio cholerae. On the basis of structures of homologous Type II/IV secretion ATPases and our biochemical data, we believe that EpsE is active as an oligomer, likely a hexamer, and the binding, hydrolysis, and release of nucleotide cause EpsE to undergo dynamic structural changes, thus converting chemical energy to mechanical work, ultimately resulting in extracellular secretion. The conformational changes that occur as a consequence of nucleotide binding would realign conserved arginines (Arg(210), Arg(225), Arg(320), Arg(324), Arg(336), and Arg(369)) from adjoining domains and subunits to complete the active site around the bound nucleotide. Our data suggest that these arginines are essential for ATP hydrolysis, although their roles in shaping the active site of EpsE are varied. Specifically, we have shown that replacements of these arginine residues abrogate the T2S process due to a reduction of ATPase activity yet do not have any measurable effect on nucleotide binding or oligomerization of EpsE. We have further demonstrated that point mutations in the EpsE intersubunit interface also reduce ATPase activity without disrupting oligomerization, strengthening the idea that residues from multiple subunits must precisely interact in order for EpsE to be sufficiently active to support T2S. Our findings suggest that the action of EpsE is similar to that of other Type II/IV secretion ATPase family members, and thus these results may be widely applicable to the family as a whole.
| S-EPMC3060491 | biostudies-literature
Project description:Aneuploidy is a condition frequently found in tumor cells but how it affects cellular physiology is not known. We have characterized one aspect of aneuploidy, the gain of extra chromosomes. We created a collection of haploid yeast strains that each bear an extra copy of one or more of almost all of the yeast chromosomes. Their characterization revealed that aneuploid strains share a number of phenotypes, including defects in cell cycle progression, increased glucose uptake and increased sensitivity to conditions interfering with protein synthesis and protein folding. These phenotypes were observed only in strains carrying additional yeast genes indicating that they reflect the consequences of additional transcription and translation as well as the resulting imbalances in cellular protein composition. We conclude that aneuploidy causes not only a proliferative disadvantage but also a set of phenotypes that is independent of the identity of the individual extra chromosomes. Keywords: CGH, gene expression
2007-05-17 | GSE7812 | GEO
Project description:Aneuploidy is a condition frequently found in tumor cells but how it affects cellular physiology is not known. We have characterized one aspect of aneuploidy, the gain of extra chromosomes. We created a collection of haploid yeast strains that each bear an extra copy of one or more of almost all of the yeast chromosomes. Their characterization revealed that aneuploid strains share a number of phenotypes, including defects in cell cycle progression, increased glucose uptake and increased sensitivity to conditions interfering with protein synthesis and protein folding. These phenotypes were observed only in strains carrying additional yeast genes indicating that they reflect the consequences of additional transcription and translation as well as the resulting imbalances in cellular protein composition. We conclude that aneuploidy causes not only a proliferative disadvantage but also a set of phenotypes that is independent of the identity of the individual extra chromosomes. Keywords: CGH, gene expression This series of microarrays compares yeast strains carrying extra chromosomes to wt yeast with normal chromosome content. Both DNA/CGH and gene expression comparisons were done, as noted. In some experiments, biological replicates were performed as noted. Reference wt nucleic acid was most commonly labeled with Cy3. Experiments labeled as "swap" have the wt reference nucleic acid labeled with Cy5, and ratio values for these experiments are reported as Cy3/Cy5.
2007-05-17 | E-GEOD-7812 | biostudies-arrayexpress
Project description:BACKGROUND:Sulfur metabolism is required for initiation of cell division, but whether or not it can actively promote cell division remains unknown. METHODOLOGY/PRINCIPAL FINDINGS:Here we show that yeast cells with more mtDNA have an expanded reductive phase of their metabolic cycle and an increased sulfur metabolic flux. We also show that in wild type cells manipulations of sulfur metabolic flux phenocopy the enhanced growth rate of cells with more mtDNA. Furthermore, introduction of a hyperactive cystathionine-beta-synthase (CBS) allele in wild type cells accelerates initiation of DNA replication. CONCLUSIONS/SIGNIFICANCE:Our results reveal a novel connection between a key sulfur metabolic enzyme, CBS, and the cell cycle. Since the analogous hyperactive CBS allele in human CBS suppresses other disease-causing CBS mutations, our findings may be relevant for human pathology. Taken together, our results demonstrate the importance of sulfur metabolism in actively promoting initiation of cell division.
| S-EPMC2776973 | biostudies-literature
Project description:Phosphoglycerate dehydrogenase (PHGDH) catalyzes the committed step in de novo serine biosynthesis. Paradoxically, PHGDH and serine synthesis are required in the presence of abundant environmental serine even when serine uptake exceeds the requirements for nucleotide synthesis. Here, we establish a mechanism for how PHGDH maintains nucleotide metabolism. We show that inhibition of PHGDH induces alterations in nucleotide metabolism independent of serine utilization. These changes are not attributable to defects in serine-derived nucleotide synthesis and redox maintenance, another key aspect of serine metabolism, but result from disruption of mass balance within central carbon metabolism. Mechanistically, this leads to simultaneous alterations in both the pentose phosphate pathway and the tri-carboxylic acid cycle, as we demonstrate based on a quantitative model. These findings define a mechanism whereby disruption of one metabolic pathway induces toxicity by simultaneously affecting the activity of multiple related pathways.
| S-EPMC6303315 | biostudies-literature
Project description:Benzimidazole derivatives of 5,6-dichlorobenzimidazole 1-?-D-ribofuranoside (DRB) comprise the important class of protein kinase CK2 inhibitors. Depending on the structure, benzimidazoles inhibit CK2 with different selectivity and potency. Besides CK2, the compounds can inhibit, with similar activity, other classical eukaryotic protein kinases (e.g. PIM, DYRK, and PKD). The present results show that a majority of the most common CK2 inhibitors can affect the atypical kinase Rio1 in a nanomolar range. Kinetic data confirmed the mode of action of benzimidazoles as typical ATP-competitive inhibitors. In contrast to toyocamycin-the first discovered small-molecule inhibitor of Rio1-the most potent representative of benzimidazoles TIBI (IC50 = 0.09 µM, K i = 0.05 µM) does not influence the oligomeric state of the Rio1 kinase. Docking studies revealed that TIBI can occupy the ATP-binding site of Rio1 in a manner similar to toyocamycin, and enhances the thermostability of the enzyme.
| S-EPMC5290066 | biostudies-literature