Regulation and conservation of the heat‐shock transcription factor σ<sup>32</sup>

Yura, Takashi

doi:10.1046/j.1365-2443.1996.28028.x

Cited by 44 publications

(33 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the increased 32 level under these conditions results primarily from stabilization and not from increased synthesis of 32 (17,39). These and other data suggested that stabilization and enhanced synthesis of 32 that occur upon exposure to high temperature involve two distinct pathways or mechanisms (11,17,43).…”

mentioning

confidence: 69%

“…Whereas induction of 32 synthesis occurs at the translation level mediated by the rpoH mRNA secondary structure (25,45), stabilization occurs presumably by sequestering 32 from DnaK and DnaJ chaperones (34,35) or proteases such as FtsH/HflB (13,37). This homeostatic response appears to be regulated by a complex feedback circuit involving chaperones, proteases, and other components of signalling pathways that have yet to be identified (2,6,11,43,44).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

et al. 1997

View full text Add to dashboard Cite

Production of abnormal proteins during steady-state growth induces the heat shock response by stabilizing normally unstable 32 (encoded by the rpoH gene) specifically required for transcription of heat shock genes. We report here that a multicopy plasmid carrying the hslVU operon encoding a novel ATP-dependent protease inhibits the heat shock response induced by production of human prourokinase (proUK) in Escherichia coli. The overproduction of HslVU (ClpQY) protease markedly reduced the stability and accumulation of proUK and thus reduced the induction of heat shock proteins. In agreement with this finding, deletion of the chromosomal hslVU genes significantly enhanced levels of proUK and 32 without appreciably affecting cell growth. When the ⌬hslVU deletion was combined with another protease mutation (lon, clpP, or ftsH/hflB), the resulting multiple mutations caused higher stabilization of proUK and 32 , enhanced synthesis of heat shock proteins, and temperature-sensitive growth. Furthermore, overproduction of HslVU protease reduced 32 levels in strains that were otherwise expected to produce enhanced levels of 32 due either to the absence of Lon-ClpXP proteases or to the limiting levels of FtsH protease. Thus, a set of ATP-dependent proteases appear to play synergistic roles in the negative control of the heat shock response by modulating in vivo turnover of 32 as well as through degradation of abnormal proteins.

show abstract

mentioning

confidence: 69%

mentioning

confidence: 99%

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

et al. 1997

View full text Add to dashboard Cite

show abstract

“…characterized as a component of the heat-shock response in Escherichia coli (reviewed by Bukau, 1993 ;Georgopoulos et al, 1994 ;Yura, 1996). In response to a sudden increase in temperature or other stresses, the levels of σ$# rise transiently because of increased synthesis and protein stabilization.…”

Section: Introductionmentioning

confidence: 99%

Identification of the heat-shock sigma factor RpoH and a second RpoH-like protein in Sinorhizobium meliloti The GenBank accession numbers for the sequences reported in this paper are AF128845 (rpoH1) and AF149031 (rpoH2).

et al. 2001

View full text Add to dashboard Cite

Hybridization to a PCR product derived from conserved sigma-factor sequences led to the identification of two Sinorhizobium meliloti DNA segments that display significant sequence similarity to the family of rpoH genes encoding the σ 32 (RpoH) heat-shock transcription factors. The first gene, rpoH1, complements an Escherichia coli rpoH mutation. Cells containing an rpoH1 mutation are impaired in growth at 37 SC under free-living conditions and are defective in nitrogen fixation during symbiosis with alfalfa. A plasmid-borne rpoH1-gusA fusion increases in expression upon entry of the culture into the stationary phase of growth. The second gene, designated rpoH2, is 42% identical to the S. meliloti rpoH1 gene. Cells containing an rpoH2 mutation have no apparent phenotype under free-living conditions or during symbiosis with the host plant alfalfa. An rpoH2-gusA fusion increases in expression during the stationary phase of growth. The presence of two rpoH-like sequences in S. meliloti is reminiscent of the situation in Bradyrhizobium japonicum, which has three rpoH genes.

show abstract

“…Analyses of the rpoH-lacZ gene fusion suggested involvement of an internal region of 32 (region C; 122-144 aa) in the control of both DnaK-DnaJ-mediated shutoff of synthesis and stability of the 32 -␤-galactosidase fusion protein (24), although core RNA polymerase binding rather than DnaK binding or 32 stability was recently shown to be affected by mutations in this region (25,26). In any event, shutoff of 32 synthesis could not be separated from the control of 32 stability, despite the clear distinction between controls of heat-induced synthesis and stability of 32 (3,4,27). In addition, the changing stability of 32 at different phases prevented accurate determination of synthesis rates during the heat-shock response.…”

mentioning

confidence: 99%

Dynamic interplay between antagonistic pathways controlling the σ ³² level in Escherichia coli

Morita

Kanemori²,

Yanagi³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

The heat-shock response in Escherichia coli depends primarily on the transient increase in the cellular level of heat-shock sigma factor 32 encoded by the rpoH gene, which results from both enhanced synthesis and transient stabilization of normally unstable 32 . Heat-induced synthesis of 32 was previously shown to occur at the translation level by melting the mRNA secondary structure formed within the 5 coding sequence of rpoH including the translation initiation region. The subsequent decrease in the 32 level during the adaptation phase has been thought to involve both shutoff of synthesis (translation) and destabilization of 32 -mediated by the DnaK-DnaJ chaperones, although direct evidence for translational repression was lacking. We now show that the heat-induced synthesis of 32 does not shut off at the translation level by using a reporter system involving translational coupling. Furthermore, the apparent shutoff was not observed when the synthesis rate was determined by a very short pulse labeling (15 s). Examination of 32 stability at 10 min after shift from 30 to 42°C revealed more extreme instability (t1/2‫02؍‬ s) than had previously been thought. Thus, the dynamic change in 32 stability during the heat-shock response largely accounts for the apparent shutoff of 32 synthesis observed with a longer pulse. These results suggest a mechanism for maintaining the intricate balance between the antagonistic pathways: the rpoH translation as determined primarily by ambient temperature and the turnover of 32 as modulated by the chaperone (and presumably protease)-mediated autogenous control.M ost organisms respond to heat or other stresses by transiently inducing molecular chaperones and other heatshock proteins (HSPs) to cope with stress-induced protein damage (1). When Escherichia coli cells are exposed to modest heat shock by a shift from 30 to 42°C, the synthesis of HSP increases for several minutes (induction phase) and gradually decreases (adaptation phase) to reach a new steady-state level within 20-30 min. The induction results from a rapid but transient increase in the cellular level of 32 (the rpoH gene product) which directs RNA polymerase to transcribe specifically from heat-shock promoters (2-4). The increase in 32 level results from both increased synthesis and stabilization of normally unstable 32 (t 1/2 ϭ 1 min), whereas the subsequent decrease in 32 has been thought to depend on shutoff of synthesis and destabilization of 32 by the DnaK-DnaJ chaperone-mediated autogenous negative control (5-9). The free pool of DnaK and͞or DnaJ was thought to act as a cellular thermometer that modulates expression of all HSPs by monitoring the state of protein folding (9-11).Heat-induced stabilization of 32 occurs rapidly although transiently. The half-life of 32 increases from 1 to 8 min for the first several minutes, and returns to about 1 min by 10 min after shift (7-9). The initial stabilization probably results from sequestering 32 away from the DnaK-DnaJ chaperones because of heat-induced accumulation of un...

show abstract

Regulation and conservation of the heat‐shock transcription factor σ³²

Cited by 44 publications

References 50 publications

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

Identification of the heat-shock sigma factor RpoH and a second RpoH-like protein in Sinorhizobium meliloti The GenBank accession numbers for the sequences reported in this paper are AF128845 (rpoH1) and AF149031 (rpoH2).

Dynamic interplay between antagonistic pathways controlling the σ ³² level in Escherichia coli

Contact Info

Product

Resources

About

Regulation and conservation of the heat‐shock transcription factor σ32

Cited by 44 publications

References 50 publications

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

Synergistic roles of HslVU and other ATP-dependent proteases in controlling in vivo turnover of sigma32 and abnormal proteins in Escherichia coli

Identification of the heat-shock sigma factor RpoH and a second RpoH-like protein in Sinorhizobium meliloti The GenBank accession numbers for the sequences reported in this paper are AF128845 (rpoH1) and AF149031 (rpoH2).

Dynamic interplay between antagonistic pathways controlling the σ 32 level in Escherichia coli

Contact Info

Product

Resources

About

Regulation and conservation of the heat‐shock transcription factor σ³²

Dynamic interplay between antagonistic pathways controlling the σ ³² level in Escherichia coli