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131.
Quantitative Proteomic Analysis of Biological Processes and Responses of the Bacterium Desulfovibrio desulfuricans ND132 upon Deletion of Its Mercury Methylation Genes
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Chen Qian Hongmei Chen Alexander Johs Xia Lu Jing An Eric M. Pierce Jerry M. Parks Dwayne A. Elias Robert L. Hettich Baohua Gu 《Proteomics》2018,18(17)
Recent studies of microbial mercury (Hg) methylation revealed a key gene pair, hgcAB, which is essential for methylmercury (MeHg) production in the environment. However, many aspects of the mechanism and biological processes underlying Hg methylation, as well as any additional physiological functions of the hgcAB genes, remain unknown. Here, quantitative proteomics are used to identify changes in potential functional processes related to hgcAB gene deletion in the Hg‐methylating bacterium Desulfovibrio desulfuricans ND132. Global proteomics analyses indicate that the wild type and ΔhgcAB strains are similar with respect to the whole proteome and the identified number of proteins, but differ significantly in the abundance of specific proteins. The authors observe changes in the abundance of proteins related to the glycolysis pathway and one‐carbon metabolism, suggesting that the hgcAB gene pair is linked to carbon metabolism. Unexpectedly, the authors find that the deletion of hgcAB significantly impacts a range of metal transport proteins, specifically membrane efflux pumps such as those associated with heavy metal copper (Cu) export, leading to decreased Cu uptake in the ΔhgcAB mutant. This observation indicates possible linkages between this set of proteins and metal homeostasis in the cell. However, hgcAB gene expression is not induced by Hg, as evidenced by similarly low abundance of HgcA and HgcB proteins in the absence or presence of Hg (500 nm ). Taken together, these results suggest an apparent link between HgcAB, one‐carbon metabolism, and metal homeostasis, thereby providing insights for further exploration of biochemical mechanisms and biological functions of microbial Hg methylation. 相似文献
132.
Redox state regulates binding of p53 to sequence-specific DNA, but not to non-specific or mismatched DNA. 总被引:1,自引:0,他引:1
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Redox modulation of wild-type p53 plays a role in sequence-specific DNA binding in vitro . Reduction produces a DNA-binding form of the protein while oxidation produces a non-DNA-binding form. Primer extension analysis reveals that increasing concentrations of reduced p53 result in enhanced protection of the consensus sequence, while increasing concentrations of oxidized p53 confer minimal protection of the consensus sequence. DNA binding by oxidized p53 is, therefore, not sequence-specific. In contrast, there is no observable difference in the binding of oxidized p53 and reduced p53 to double-stranded non-specific or mismatched DNA in gel mobility shift assays. Both forms of p53 bind equally well, suggesting that redox modulation of p53 does not play a role in its binding to non-specific or mismatched DNA. In view of the in vitro evidence that redox state influences the sequence-specific DNA-binding of p53, we have examined the effect of oxidative stress on the in vivo ability of p53 to bind to and transactivate PG13-CAT, a reporter construct containing multiple copies of the p53 consensus binding site linked to the chloramphenicol acetyltransferase gene. Hydrogen peroxide treatment of cells cotransfected with p53 results in a marked decrease in CAT activity, suggesting that oxidation of p53 decreases the ability of the protein to bind to consensus DNA and transactivate target genes in vivo. 相似文献
133.
Camellia japonica is a widespread and morphologically diverse tree native to parts of Japan and adjacent islands. Starch gel electrophoresis was used to score allelic variation at 20 loci in seeds collected from 60 populations distributed throughout the species range. In comparison with other plant species, the level of genetic diversity within C. japonica populations is very high: 66.2% of loci were polymorphic on average per population, with a mean number of 2.16 alleles per locus; the mean observed and panmictic heterozygosities were 0.230 and 0.265, respectively. Genotypic proportions at most loci in most populations fit Hardy-Weinberg expectations. However, small heterozygote deficiencies were commonly observed (mean population fixation index = 0.129). It is suggested that the most likely cause of the observed deficiencies is population subdivision into genetically divergent subpopulations. The overall level of population differentiation is greater than is typically observed in out-breeders: The mean genetic distance and identity (Nei's D and I) between pairs of populations were 0.073 and 0.930, respectively, and Wright's Fst was 0.144. Differences among populations appeared to be manifested as variation in gene frequencies at many loci rather than variation in allelic composition per se. However, the patterns of variation were not random. Reciprocal clinal variation of gene frequencies was observed for allele pairs at six loci. In addition, principal components analysis revealed that populations tended to genetically cluster into four regions representing the geographic areas Kyushu, Shikoku, western Honshu, and eastern Honshu. There was a significant relationship between genetic and geographic distance (r = 0.61; P < 0.01). Analysis of variance on allozyme frequencies showed that there was approximately four times as much differentiation among populations within regions, as among regions. It is likely that the observed patterns of population relationships result from the balance between genetic drift in small subpopulations and gene flow between them. 相似文献
134.
Foliar extracts of high elevation Quercus rubra contain 20 major flavonol-3-0-glycosides based primarily on the aglycones myricetin, quercetin, and kaempferol. These compounds display an altitudinal cline in the Appalachian mountains, with quercetin-rich low elevation chemotypes intergrading into myricetin-rich high elevation forms. These chemotypes appear to be correlated with previously documented variation in foliar morphology. The degree of interpopulation variation also differs with elevation. At higher elevations flavonoids differ only quantitatively between sites, while below 3,000 ft there is site-to-site variability in the hydroxylation level of the aglycones. 相似文献
135.
Arrhenius kinetics of two mitochondrial enzymes, cytochrome oxidase and S-adenosylmethionine: Δ 24 sterol methyltransferase were analyzed in wild-type and sterol mutant strains of yeast. Temperature effects on the enzymes isolated from the ergosterol producing wild-type and nystatin resistant mutants (major sterol Δ8(9), 22 ergostadiene-3-β-ol) were compared. Transition temperatures were lower in both mutant strains compared to wild-type. Lipid analysis shows a relationship between sterol content and the temperature dependent transition phases. 相似文献
136.
Effect of Putative Deoxyribonucleic Acid Inhibitors on Macromolecular Synthesis in Saccharomyces cerevisiae 总被引:4,自引:1,他引:3
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The effects of inhibitors of bacterial deoxyribonucleic acid (DNA) synthesis upon logarithmically growing cultures of Saccharomyces cerevisiae were investigated. Cell division, ribonucleic acid (RNA) synthesis, and DNA synthesis were measured after addition of nalidixic acid, fluorodeoxyuridine, or phenethyl alcohol to cultures of yeast growing in defined and complex media. Both nalidixic acid and fluorodeoxyuridine had only temporary effects on nucleic acid synthesis in cultures growing in defined medium, and little or no observable effect on cultures growing in complex medium. Neither compound inhibited colony formation on complex solid medium, although growth was slow on defined solid medium. Phenethyl alcohol caused complete inhibition of DNA synthesis, RNA synthesis, and cell division in cultures growing in defined medium. In cultures growing in complex medium, RNA synthesis and cell division were inhibited to a lesser extent. A slight increase in DNA was observed in the presence of the inhibitor. 相似文献
137.
Immunological Cross-Reactions Between Two Low-Molecular-Weight Polypeptides from A Murine Type C Virus 总被引:2,自引:2,他引:0
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Wade P. Parks Edward M Scolnick Marian C. Noon Cynthia J. Watson 《Journal of virology》1974,14(3):430-433
Two low-molecular-weight type-specific virion polypeptides from the Kirsten strain of Murine leukemia virus, polypeptides p10 and p12, are immunologically related by radioimmunoassay competition techniques. 相似文献
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