Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heat shock leads to co-ordinate increases in transcription of a family of heat shock genes, including the mouse hsp70.1 and B2 genes. Activation of the heat shock transcription factor (HSF) by heat shock stimulates transcription of the murine hsp70.1 gene (by RNA polymerase II). B2 genes are short, repetitive sequences whose transcription (by RNA polymerase III) are also increased after heat shock. We have studied whether heat-induced transcription is auto-regulated by the products of the heat shock genes. The results indicate: (1) after an initial heat shock, transcription of the heat shock genes by RNA polymerases II and III becomes desensitized to further heat shock, and the heat-induced DNA binding activity of the HSF is lost, (2) if accumulation of heat shock gene products is inhibited, the desensitizing effect of a prior heat shock is removed, and (3) transcription of the hsp70.1 and B2 genes apparently involves different mechanisms, with hsp70.1 employing the HSF and the B2 gene using a separate, heat-activated transcriptional mechanism. However, the level of transcription from the hsp70.1 and B2 genes and the stability of their respective RNAs are co-ordinately regulated by the level of heat shock protein in the cell. The data indicate that auto-regulation of the level of mouse heat shock gene products is mediated by RNA polymerase II transcripts but that the regulatory mechanism can control transcription from RNA polymerase III genes as well.
...
PMID:Heat-induced transcription from RNA polymerases II and III and HSF binding activity are co-ordinately regulated by the products of the heat shock genes. 138 51

Escherichia coli K-12 produces at least two ATP-dependent proteases, Lon (La) and Clp (Ti), the latter consisting of a regulatory subunit (ClpA) and a proteolytic subunit (ClpP). The gene clpB encoding an analog of ClpA had been found at 57 min on the E. coli chromosome. Cloning and examination of novel heat shock promoters led us to identify a major clpB promoter specifically controlled by a heat shock sigma factor, sigma 32 (the rpoH [= htpR] gene product). beta-Galactosidase synthesis from a PclpB-lacZ operon fusion was transiently induced upon temperature shift from 30 to 42 degrees C, and the induction depended on the rpoH function. Chromosomal clpB transcripts also increased upon temperature upshift and were totally absent in the rpoH deletion strain. In the in vitro transcription experiments, the clpB promoter was specifically recognized and transcribed by RNA polymerase-sigma 32. Nucleotide sequencing and determination of mRNA start sites permitted us to identify a major heat shock promoter located upstream of the clpB coding sequence. The results clearly indicate that clpB expression is under direct control of sigma 32. Since ClpP was recently shown to be a sigma 32-dependent heat shock protein, the present finding suggests the possibility that a potential ATP-dependent protease, ClpB-ClpP complex, plays an important role against thermal stress in E. coli.
...
PMID:Expression of ClpB, an analog of the ATP-dependent protease regulatory subunit in Escherichia coli, is controlled by a heat shock sigma factor (sigma 32). 190 60

The effects of IFN and mild hyperthermia on the responses of human promyelocytic HL-60 cells were investigated. Cells subjected to an elevated culture temperature (39.5 degrees-40.5 degrees C instead of 37 degrees C, herein referred to as heat-treated cells) showed an increase in heat shock proteins (HSPs) and corresponding mRNA synthesis, which were additionally potentiated by the presence of IFN. With cells cultured at 37 degrees C, IFN had no effect on HSP expression. The observed inhibition (40-70%) of RNA polymerase II-directed RNA synthesis (based on alpha-amanitin sensitivity) in isolated nuclei of heat-treated cells was also significantly reversed by the simultaneous addition of IFN. These data suggest that the IFN-amplified HSP gene expression may be involved in preventing irreversible damage or in fine tuning the recovery of mammalian cells from heat stress.
...
PMID:Enhanced expression of heat shock protein and mRNA synthesis by type I interferon in human HL-60 leukemic cells. 193 Feb 53

sigma 32, the product of the Escherichia coli rpoH locus, is an alternative RNA polymerase sigma factor utilized to express heat shock genes upon a sudden rise in temperature. E. coli K165 [rpoH165(Am) supC(Ts)] is temperature sensitive for growth and does not induce heat shock protein synthesis. We have isolated a locus from Rhizobium meliloti called suhR that allows E. coli K165 to grow at high temperature and induce heat shock protein synthesis. R. meliloti suhR mutants were viable and symbiotically effective. suhR was found to have no DNA or derived amino acid sequence similarity to the genes of previously sequenced sigma factors or other data base entries, although a helix-turn-helix DNA-binding protein motif is present. suhR did not restore the phenotypic defects of delta rpoH E. coli; suppression of the E. coli K165 phenotype is thus likely to involve E. coli sigma 32. Western immunoblots showed that suhR caused an approximately twofold elevation of sigma 32 levels in K165; RNA blots indicated that rpoH mRNA level and stability were not altered. Stabilization of sigma 32 protein and increased rpoH mRNA translation are thus the most probable mechanisms of suppression.
...
PMID:Rhizobium meliloti suhR suppresses the phenotype of an Escherichia coli RNA polymerase sigma 32 mutant. 211 6

The transcriptional activity of the topA gene which codes for topoisomerase I was examined. An in vitro assay determined that the P1 promoter was dependent on the sigma 32 subunit of RNA polymerase. The transcriptional activity of the four topA promoters was examined by nuclease S1 mapping of the transcripts during a heat shock. This sigma 32-dependent promoter was shown to function as a heat shock promoter, although topoisomerase I is not a heat shock protein. A possible method of compensation of transcription activity by the other promoters to maintain the level of topoisomerase I during heat shock is proposed.
...
PMID:Identification of a heat shock promoter in the topA gene of Escherichia coli. 217 62

The Escherichia coli DnaK heat shock protein has been identified previously as a negative regulator of E. coli heat shock gene expression. We report that two other heat shock proteins, DnaJ and GrpE, are also involved in the negative regulation of heat shock gene expression. Strains carrying defective dnaK, dnaJ, or grpE alleles have enhanced synthesis of heat shock proteins at low temperature and fail to shut off the heat shock response after shift to high temperature. These regulatory defects are due to the loss of normal control over the synthesis and stability of sigma 32, the alternate RNA polymerase sigma-factor required for heat shock gene expression. We conclude that DnaK, DnaJ, and GrpE regulate the concentration of sigma 32. We suggest that the synthesis of heat shock proteins is controlled by a homeostatic mechanism linking the function of heat shock proteins to the concentration of sigma 32.
...
PMID:DnaK, DnaJ, and GrpE heat shock proteins negatively regulate heat shock gene expression by controlling the synthesis and stability of sigma 32. 226 29

In transient expression assays, the adenovirus E1B 19-kilodalton (19K) tumor antigen increases expression from viral promoters and the promoter for the cellular 70-kilodalton heat shock protein (hsp70). To study the mechanism of this effect, we constructed HeLa cell lines that contain stably integrated copies of the 19K gene. Compared with a 19K- control cell line, 19K+ cells produced a significantly higher level of expression from every promoter introduced into the cells by transfection. The 19K protein also increased expression of an RNA polymerase III-transcribed gene but did not affect the level of expression of the endogenous hsp70 gene. The rate of transcription from transfected promoters, as measured by a nuclear run-on assay, was higher in the 19K+ cells than in the 19K- control cells. Furthermore, the level of plasmid DNA remained higher in the 19K+ cell line, suggesting that the 19K protein stabilizes transfected plasmid DNA. The elevated DNA levels seemed to account in full for the increased transcription. The role of the 19K protein in increasing gene expression during viral infection was found to be due to a replication-dependent increase in viral DNA levels. Thus, the 19K protein activates transcription indirectly by producing a higher level of viral or plasmid DNA. The DNA stabilization function of the 19K protein is probably related to the protective role of the 19K protein during viral infection and represents the first example of a viral oncogene product that modulates gene expression by regulating viral and plasmid DNA levels.
...
PMID:The adenovirus E1B 19-kilodalton protein stimulates gene expression by increasing DNA levels. 253 Dec 84

We have investigated the induction of known hsp (heat shock protein) RNA and other heat shock (HS) inducible transcripts in Chinese hamster cells by various stresses including DNA damaging agents. cDNA clones coding for at least 14 different HS-inducible transcripts were isolated. By DNA sequence analysis and homology with cDNA clones of other species, some of these cDNA clones were identified as coding for hsp27, hsp89 alpha, hsp89 beta, two different hsp70s, ubiquitin, and the HS-inducible RNA polymerase III transcript B2. In addition, hsp-related cDNA clones, hsp60 and four with hsp70 homology, were isolated which coded for transcripts which were not induced by HS or other stresses in two different Chinese hamster cell lines. After HS or treatment with the HS-mimetic agent ethanol, there was coordinate induction of all 14 transcripts. With severe HS treatments which produced substantial cytotoxicity, the increase in all transcripts except B2 RNA was delayed and, in some cases, suppressed. The only DNA damaging agent, which induced many HS-inducible transcripts, was high-dose methylmethane sulfonate (MMS). However, induction by MMS was not coordinate for all transcripts as it was for HS, and B2 RNA was not induced. hsp27 RNA induction differed from the others in several respects including induction by irradiation and other agents which produce high levels of DNA damage repaired by nucleotide excision repair. The implications of these findings in cellular events such as cytotoxicity, thermotolerance, and regulation of stress responses will be discussed.
...
PMID:Induction of heat shock protein transcripts and B2 transcripts by various stresses in Chinese hamster cells. 254 Oct 7

The expression of heat shock genes in Escherichia coli is controlled by the action of an alternate sigma-factor of RNA polymerase, sigma 32, which directs core RNA polymerase to recognize the promoters for heat shock genes. After a shift from 30 degrees C to 42 degrees C, both the level of sigma 32 and transcription initiation at heat shock promoters transiently increase, indicating that heat shock gene expression is regulated by changes in the concentration of sigma 32. Here, we report that heat shock gene expression is regulated by changes in the activity of sigma 32 under some conditions. Our results show that the transient repression of heat shock protein synthesis, which follows a shift down from 42 degrees C to 30 degrees, occurs as a result of decreased transcription initiation at heat shock promoters, but this repression is accompanied by only a small decrease in the level of sigma 32. In addition, the induction of heat shock proteins following overproduction of sigma 32 from a multicopy plasmid is only transient, despite the fact that the level of sigma 32 remains elevated. Constitutive overproduction of sigma 32 also fails to cause a proportionate increase in heat shock gene transcription. These three examples suggest that the activity of sigma 32 is reduced under conditions of excess heat shock gene expression.
...
PMID:The activity of sigma 32 is reduced under conditions of excess heat shock protein production in Escherichia coli. 269 91

The general properties of the heat shock response in Pseudomonas aeruginosa were characterized. The transfer of cells from 30 to 45 degrees C repressed the synthesis of many cellular proteins and led to the enhanced production of 17 proteins. With antibodies raised against the Escherichia coli proteins, two polypeptides of P. aeruginosa with apparent molecular weights of 76,000 and 61,000 (76K and 61K proteins) were shown to be analogous to the DnaK and GroEL heat shock proteins of E. coli due to their immunologic cross-reactivity. The major sigma factor (sigma 87) of P. aeruginosa was shown to be a heat shock protein that was immunologically related to the sigma 70 of E. coli by using polyclonal antisera. A hybridoma was produced, and the monoclonal antibody MP-S-1 was specific for the sigma 87 and did not cross-react with sigma 70 of E. coli. A smaller 40K protein was immunoprecipitated with RNA polymerase antisera from cells that had been heat shocked. The 40K protein was also associated with RNA polymerase which had been purified from heat-shocked cells and may be the heat shock sigma factor of P. aeruginosa. Exposure to ethanol resulted in the production of seven new proteins, three of which appeared to be heat shock proteins.
...
PMID:Heat shock response of Pseudomonas aeruginosa. 313 46


1 2 3 4 5 6 Next >>

---