Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The E. coli PriA protein, a DEXH-type DNA helicase with unique zinc finger-like motifs interrupting the helicase domains, is an essential component of the phiX174-type primosome and plays critical roles in RecA-dependent inducible and constitutive stable DNA replication (iSDR and cSDR, respectively) as well as in recombination-dependent repair of double-stranded DNA breaks. B. subtilis PriA (BsPriA) protein contains the conserved helicase domains as well as zinc finger-like motifs with 34% overall identity with the E. coli counterpart. We overexpressed and purified BsPriA and examined its biochemical properties. BsPriA binds specifically to both n'-pas (primosome assembly site) and D-loop and hydrolyzes ATP in the presence of n'-pas albeit with a specific activity about 30% of that of E. coli PriA. However, it is not capable of supporting n'-pas-dependent replication in vitro, nor is it able to support ColE1-type plasmid replication in vivo which requires the function of the phiX174-type primosome. We also show that a zinc finger mutant is not able to support recombination-dependent DNA replication, as measured by the level of iSDR after a period of thymine starvation, nor wild-type level of growth, cell morphology and UV resistance. Unexpectedly, we discovered that an ATPase-deficient mutant (K230D) is not able to support iSDR to a full extent, although it can restore normal growth rate and UV resistance as well as non-filamentous morphology in priA1::kan mutant. K230D was previously reported to be fully functional in assembly of the phiX174-type primosome at a single-stranded n'-pas. Our results indicate that ATP hydrolysis/ helicase activity of PriA may be specifically required for DNA replication from recombination intermediates in vivo.
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PMID:Escherichia coli and Bacillus subtilis PriA proteins essential for recombination-dependent DNA replication: involvement of ATPase/helicase activity of PriA for inducible stable DNA replication. 1057 98

Werner syndrome (WS) is a rare autosomal recessive genetic disorder causing premature aging and rare cancers. A gene responsible for WS (WRN) encodes a protein with 1432 amino acids (a.a.) homologous to the E. coli RecQ-type DNA helicase. Transcriptional activation facilitated nucleolar localization of human WRN protein (hWRNp) and serum starvation induced translocation of hWRNp from the nucleoli to the nucleoplasm in human cultured cells, suggesting a nucleolar-nucleoplasm trafficking of hWRNp depending on transcriptional state. Mutant hWRNp lacking the C-terminal 30 a.a. residues (Delta1403-1432) failed to localize in the nucleolus, whereas Delta1405-1432 can migrate into the nucleolus. Here we identify a region putative for nucleolar localization signal (NoLS) containing a sequence of two positively charged amino acids (Arg(1403)-Lys(1404)) in the C-terminal area of hWRNp. By contrast, the mouse homolog (mWRNp) exists only in the nucleoplasm. We show that the inability of mWRNp to migrate into the nucleolus is due to a difference of a sequence in the region corresponding to the NoLS of hWRNp. In addition, mouse cells cannot recognize the NoLS of hWRNp. Our study suggests that defect in nucleolar function of hWRNp may be linked to the premature aging which is not observed in mWRN(-/-) mice.
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PMID:Diverged nuclear localization of Werner helicase in human and mouse cells. 1142 Jun 65

Maintaining the integrity of genetic information is fundamental for the life of a cell and the survival of a species. Cells can encounter DNA damage as a consequence of normal cellular metabolism or as a result of exposure to chemical or physical agents. Eukaryotic cells have developed a network of responses in order to deal with DNA damage thereby preserving the integrity of their genetic information. In the presence of extensive genetic insult, a surveillance mechanism or "checkpoint" is activated. The activation of this signal transduction pathway leads to an arrest of cell cycle progression to prevent replication and segregation of damaged DNA molecules and to induce transcription of several repair genes. Existing repair mechanisms are also mobilised, in a coordinated effort to restore the original DNA structure. Genes involved in either cell cycle checkpoints, DNA repair or genes that maintain the fidelity of chromosome segregation are often termed "antimutators" or "caretaker" genes, because they control the stability of the genome and prevent accumulation of mutations in so-called "gatekeeper" genes. This latter group of genes directly regulate the growth of tumours either by inhibiting growth or promoting death. A fundamental requirement for many DNA metabolism processes is the separation of the complementary strands of the DNA duplex. This is promoted by DNA helicases, which unwind nucleic-acid duplexes in an ATP-dependent manner to provide access to the template for proteins of the replication, recombination, repair and transcription machineries. Multiple DNA helicase families have been identified, all containing seven hallmark helicase motifs; members within each helicase family also share sequence homologies beyond and between these motifs. One example is the RecQ helicase family, named after the RecQ protein of Escherichia coli, which was identified during a search for mutants sensitive to thymine starvation. Five members of the RecQ family have been identified in the human genome, and mutations in three of the genes are responsible for genetic diseases that are characterised by genomic instability and a high incidence of cancer. Because mutants in RecQ family genes in other species also have unstable chromosomes, it was proposed that members of the RecQ helicase family play a central role in the maintenance of genomic stability and thereby the prevention of tumorigenesis.
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PMID:RecQ helicases and genome stability: lessons from model organisms and human disease. 1245 1

Yeast Pif1 DNA helicase is the prototype member of a helicase subfamily participating in the maintenance of telomere, ribosome, and mitochondria DNAs. The Pif1 DNA helicase family is highly conserved from yeast to human, but the biochemical nature of human homologues remains to be clarified. To this end, we investigated the transcriptional unit of human Pif1 gene and its encoded protein hPif1. The results showed that the hPif1 gene product has at least two isoforms consisting of the conserved helicase motif and differential C-terminal regions derived from alternative splicing of the gene transcript. Deletion mutant analysis showed that Pif1 helicase has nuclear localization signal and mitochondria targeting signal at the N-terminal and C-terminal regions, respectively. In HeLa cells, hPif1 helicase expression was induced by the release of cells from serum starvation, suggesting that hPif1 has roles in the S phase. Consistently, the down regulation of the hPif1 helicase by RNA interference with siRNA caused a cell cycle delay at the S phase. These findings suggest that hPif1 in the nucleus may be involved in chromosome maintenance in association with DNA replication, while the function of hPif1 remains to be clarified.
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PMID:Mitochondrial and nuclear localization of human Pif1 helicase. 1782 21

Industrial yeasts, economically important microorganisms, are widely used in diverse biotechnological processes including brewing, winemaking and distilling. In contrast to a well-established genome of brewer's and wine yeast strains, the comprehensive evaluation of genomic features of distillery strains is lacking. In the present study, twenty two distillery yeast strains were subjected to electrophoretic karyotyping and array-based comparative genomic hybridization (array-CGH). The strains analyzed were assigned to the Saccharomyces sensu stricto complex and grouped into four species categories: S. bayanus, S. paradoxus, S. cerevisiae and S. kudriavzevii. The genomic diversity was mainly revealed within subtelomeric regions and the losses and/or gains of fragments of chromosomes I, III, VI and IX were the most frequently observed. Statistically significant differences in the gene copy number were documented in six functional gene categories: 1) telomere maintenance via recombination, DNA helicase activity or DNA binding, 2) maltose metabolism process, glucose transmembrane transporter activity; 3) asparagine catabolism, cellular response to nitrogen starvation, localized in cell wall-bounded periplasmic space, 4) siderophore transport, 5) response to copper ion, cadmium ion binding and 6) L-iditol 2- dehydrogenase activity. The losses of YRF1 genes (Y' element ATP-dependent helicase) were accompanied by decreased level of Y' sequences and an increase in DNA double and single strand breaks, and oxidative DNA damage in the S. paradoxus group compared to the S. bayanus group. We postulate that naturally occurring diversity in the YRF1 gene copy number may promote genetic stability in the S. bayanus group of distillery yeast strains.
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PMID:Genome-wide array-CGH analysis reveals YRF1 gene copy number variation that modulates genetic stability in distillery yeasts. 2638 47

The spatiotemporal organization of chromatin plays central roles in cellular function. The ribosomal DNA (rDNA) chromatin undergoes dynamic structural changes during mitosis and stress. Here, we developed a CRISPR-based imaging system and tracked the condensation dynamics of rDNA chromatin in live yeast cells under glucose starvation. We found that acute glucose starvation triggers rapid condensation of rDNA. Time-lapse microscopy revealed two stages for rDNA condensation: a "primary stage," when relaxed rDNA chromatin forms higher order loops or rings, and a "secondary stage," wehen the rDNA rings further condense into compact clusters. Twisting of rDNA rings accompanies the secondary stage. The condensin complex, but not the cohesin complex, is required for efficient rDNA condensation in response to glucose starvation. Furthermore, we found that the DNA helicase Sgs1 is essential for the survival of cells expressing rDNA-bound dCas9, suggesting a role for helicases in facilitating DNA replication at dCas9-binding sites.
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PMID:Live-Cell Imaging of Chromatin Condensation Dynamics by CRISPR. 3002 55