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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A diminution of RNA content in hen liver nuclei was observed after either prolonged starvation or short-term exposure to alpha-amanitin. Using polyacrylamide gel electrophoresis, it has been revealed a limited number of altered polypeptide bands in the gel patterns of 0.35 M NaCl- and 5 M urea-soluble non-histone proteins from liver chromatin of starved or alpha-amanitin-treated birds. The low-molecular-weight polypeptides were found to increase in the protein fractions from liver chromatin of alpha-amanitin-injected hens. Only two protein bands (48 and 79 kDa) in the gel patterns of 5 M urea-soluble chromatin fraction altered in similar manner both in starved and alpha-amanitin-treated animals. The amount of the 48-kDa protein decreased and that of the 79-kDa protein increased under these conditions. alpha-Amanitin seems to affect differently the non-histone chromatin proteins from starved and fed animals. The level of the 48-kDa urea-soluble protein was lower and that of the 64-kDa protein was higher in liver chromatin of starved animals receiving alpha-amanitin in comparison with the corresponding proteins from fed animals treated with this drug.
Gen Pharmacol 1987
PMID:Effect of alpha-amanitin on liver non-histone chromatin proteins of starved hens. 244 Jul 60

Previous studies on two Escherichia coli rpoB mutants, carrying single amino acid substitutions at approximate amino acid positions 736 and 906 in the beta subunit, showed that these alterations in the RNA polymerase resulted in an apparent reduced response to valine-induced amino acid starvation in vivo and prevented ppGpp-mediated inhibition of transcriptional initiation at stable RNA promoters in vitro. These observations suggested that the mutations had altered either the ppGpp binding site or the promoter selectivity of the enzyme. The in vivo analysis presented here indicates that these mutants encode an RNA polymerase that responds normally to changes in the level of ppGpp; their apparent relaxedness is due to a reduced accumulation of ppGpp during isoleucine starvation. Thus, there is no indication that the mutations have altered ppGpp binding sites. These observations and the difference between in vitro and in vivo results can be explained by the assumption that the mutations produce an extended ppGpp-dependent pausing of RNA polymerase during the transcription of unstable RNA. Comparison of the vivo and in vitro effects of ppGpp on rrn transcription further suggests that these reflect different phenomena, although in both cases ppGpp inhibits rrn transcription.
Mol Gen Genet 1988 Aug
PMID:Studies in vivo on Escherichia coli RNA polymerase mutants altered in the stringent response. 246 Jul 32

The plasma-membrane ATPase of Saccharomyces cerevisiae is a proton pump whose activity, essential fro proliferation, is subject to regulation by nutritional signals. The previous finding that the CDC25 gene product is required for the glucose-induced H+-ATPase activation suggested that H+-ATPase activity is regulated by cAMP. Analysis of starvation-induced inactivation and glucose-induced activation of the H+-ATPase in mutants affected in activity of the RAS proteins, adenylyl cyclase or cAMP-dependent protein kinase showed that nutritional regulation of H+-ATPase activity does not depend directly on any of these factors. We conclude that adenlyl cyclase does not mediate all nutritional responses. This also indicates that the specific CDC25 requirement for the glucose-induced activation of the H+-ATPase identifies a new function for the CDC25 gene product, a function that appears to be independent of CDC25-mediated modulation of the RAS/adenylyl cyclase/cAMP pathway.
J Gen Microbiol 1989 Jun
PMID:cAMP- and RAS-independent nutritional regulation of plasma-membrane H+-ATPase activity in Saccharomyces cerevisiae. 255 50

The GLN1 gene of Saccharomyces cerevisiae was cloned by complementation of a gln1 auxotroph. A GLN1-lacZ fusion was constructed to assay GLN1 promoter activity. beta-Galactosidase and glutamine synthetase expression in chromosomally integrated GLN1-lacZ fusion strains were co-regulated in response to a shift from glutamine to glutamate as the nitrogen source, purine limitation, and 3-aminotriazole-induced histidine starvation. Regulation of GLN1 expression by each of the three pathways occurred at the transcriptional level. Increased accumulation of GLN1 mRNA was observed within 5 min after a shift from glutamine to glutamate as the nitrogen source. After 5 min, GLN1 mRNA levels were constant. The level of GLN1 transcript was reduced by approximately 75% within 5 min following glutamine addition to the cells growing with glutamate as nitrogen source. This indicates that the GLN1 message is unstable and has a half-life of approximately 3 min. Deletion analysis indicated that the sequences required for GLN1 expression are located within approximately 350 bp upstream from the transcriptional initiation site.
Mol Gen Genet 1989 Jun
PMID:Three regulatory systems control expression of glutamine synthetase in Saccharomyces cerevisiae at the level of transcription. 257 Mar 48

An electrophoretic system capable of separating 25 S, 23 S, 17.5 S and 16 S ribosomal RNA (rRNA) species was used to study the synthesis and fate of rRNA during amino acid starvation and resupplementation of E. coli relaxed strain KL99. This E. coli relAl strain responded to an amino acid starvation by increasing the rate of synthesis of 25 S and 17.5 S precursor rRNA. When the limiting amino acid was resupplemented, a previously observed 40-fold increase in the cellular guanosine 5'-diphosphate, 3'-diphosphate content [Mol. Gen. Genet. (1983) 192, 5-9] appeared to cause a reduction in new rRNA synthesis. Following amino acid resupplementation, the precursor 25 S and 17.5 S rRNA accumulated during the amino acid starvation were conserved and processed to 23 S and 16 S rRNA species, respectively. This suggests that a modified ribosome assembly scheme involving stable precursor rRNA exists in relAl bacteria during periods of amino acid limitation and resupplementation.
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PMID:Processing of precursor ribosomal RNA and the presence of a modified ribosome assembly scheme in Escherichia coli relaxed strain. 257 53

This study describes the isolation and characterization of a mutant (strain GP122) of Salmonella typhimurium with a partial deficiency of phosphoribosylpyrophosphate (PRPP) synthetase activity. This strain was isolated in a purE deoD gpt purin auxotroph by a procedure designed to select guanosine-utilizing mutants. Strain GP122 had roughly 15% of the PRPP synthetase activity and 25% of the PRPP pool of its parent strain. The mutant exhibited many of the predicted consequences of a decreased PRPP pool and a defective PRPP synthetase enzyme, including: poor growth on purine bases; decreased accumulation of 5-aminoimidazole ribonucleotide (the substrate of the blocked purE reaction) under conditions of purine starvation; excretion of anthranilic acid when grown in medium lacking tryptophan; increased resistance to inhibition by 5-fluorouracil; derepressed levels of aspartate transcarbamylase and orotate phosphoribosyltransferase, enzymes involved in the pyrimidine de novo biosynthetic pathway; growth stimulation by PRPP-sparing compounds (e.g. guanosine, histidine); poor growth in low phosphate medium; and increased heat lability of the defective enzyme. This mutant strain also had increased levels of guanosine 5'-monophosphate reductase. This genetic lesion, designated prs, was mapped by conjugation and phage P22-mediated transduction at 35 units on the Salmonella linkage map.
J Gen Microbiol 1985 Feb
PMID:Characterization of a Salmonella typhimurium mutant defective in phosphoribosylpyrophosphate synthetase. 258 45

RNA synthesis was followed during amino acid starvation of strains of Escherichia coli that contained both the relaxed (relA) mutation and a mutation affecting ribosome assembly that results in oversynthesis of RNA. The ribosome mutation did not by itself lead to relaxedness. The relaxed mutation could be expressed in organisms that contained the ribosome mutation.
J Gen Microbiol 1985 Apr
PMID:Interactions between mutations affecting ribosome synthesis in Escherichia coli. 258 Sep 43

Erythropoietic responses of fed and starved species of teleosts, viz., Clarias batrachus and Heteropneustes fossilis, to human urinary erythropoietin and thyroxine have been examined. The effects of these hormones on energy reserves have also been evaluated. Twenty-four C. batrachus were divided into two groups: half were fed regularly; the remaining fish were starved 20 days. On the 21st day each group was further divided into three subgroups of four each and received either saline, thyroxine (8 micrograms), or erythropoietin (6 IU) over 4 consecutive days. The experimental protocol was identical for H. fossilis; however, for H. fossilis two identical studies were conducted approximately 1 year apart. A decline in the rate of erythropoiesis and a stimulatory response to human urinary erythropoietin followed starvation in both species of teleosts. In addition, erythropoietin had a pronounced effect on hepatic glycogenesis of fed H. fossilis and stimulated erythropoiesis in the fed teleosts of both species. Prolonged starvation drastically depleted hepatic glycogen in C. batrachus. In contrast, it had no effect on hepatic glycogen in H. fossilis and on muscle glycogen and protein in both species. In general, while both species could respond to erythropoietin and withstand prolonged starvation, H. fossilis alone exhibited remarkable tolerance to fasting.
Gen Comp Endocrinol 1989 Dec
PMID:Influence of human urinary erythropoietin and L-thyroxine on blood morphology and energy reserves in two tropical species of fed and starved teleosts. 258 68

Cells of Streptococcus sanguis strain Challis were incubated with sodium lauroylsarcosinate to extract surface proteins. A polypeptide of apparent molecular mass 16 kDa comprising about 12% of the extract was purified using anion-exchange chromatography. The polypeptide was shown to be a phosphocarrier protein (HPr) that could also be found in the soluble (cytoplasmic) fraction from cells broken by homogenization with glass beads. In vivo labelling of S. sanguis cells with 32Pi showed that the polypeptide carried a heat- and acid-stable phosphorylation and that during sucrose starvation the HPr became dephosphorylated. Antiserum raised to the S. sanguis HPr reacted on Western blots with HPrs from all oral streptococci tested, together with strains of S. pyogenes and S. salivarius, but not with HPrs from S. faecalis or S. bovis, nor with proteins from Staphylococcus aureus, Bacillus subtilis, Actinomyces viscosus and various lactobacilli. The S. sanguis HPr had a high content of alanine (17.2%) and was similar in overall amino acid composition to the HPrs from S. mutans an S. salivarius. The N-terminal residues (to 37) of the S. sanguis HPr showed strong sequence identity (82%) with the N-terminal sequence of S. faecalis HPr. It is suggested that HPr in S. sanguis is associated closely with the cytoplasmic membrane. Non-disruptive methods of removing cell-surface proteins from streptococci effect release of HPr and possibly other cytoplasmic components.
J Gen Microbiol 1989 Dec
PMID:Properties of a phosphocarrier protein (HPr) extracted from intact cells of Streptococcus sanguis. 263 56

The pstS gene belongs to the phosphate regulon whose expression is induced by phosphate starvation and regulated positively by the PhoB protein. The phosphate (pho) box is a consensus sequence shared by the regulatory regions of the genes in the pho regulon. We constructed two series of deletion mutations in a plasmid in vitro, with upstream and downstream deletions in the promoter region of pstS, which contains two pho boxes in tandem, and studied their promoter activity by connecting them with a promoterless gene for chloramphenicol acetyltransferase. Deletions extending into the upstream pho box but retaining the downstream pho box greatly reduced promoter activity, but the remaining activity was still regulated by phosphate levels in the medium and by the PhoB protein, indicating that each pho box is functional. No activity was observed in deletion mutants which lacked the remaining pho box or the -10 region. Therefore, the pstS promoter was defined to include the two pho boxes and the -10 region. The PhoB protein binding region in the pstS regulatory region was studied with the deletion plasmids by a gel-mobility retardation assay. The results suggest the protein binds to each pho box on the pstS promoter. A phoB deletion mutant was constructed, and we demonstrated that expression of pstS was strictly dependent on the function of the PhoB protein.
Mol Gen Genet 1989 Feb
PMID:Regulation of the phosphate regulon of Escherichia coli: characterization of the promoter of the pstS gene. 265 88


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