English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The heat shock response in alpha proteobacteria is unique in that a combination of two regulators is involved: a positive regulator, RpoH (ς32 homolog), found in the alpha, beta, and gamma proteobacteria, and a negative regulator, HrcA, widely distributed in eubacteria but not in the gamma proteobacteria. To assess the differential roles of the two regulators in these bacteria, we cloned thehrcA-grpE operon ofAgrobacterium tumefaciens , analyzed its transcription, and constructed deletion mutants lacking RpoH and/or HrcA. TheΔrpoH mutant andΔrpoH ΔhrcA double mutant were unable to grow above 30°C. Whereas the synthesis of heat shock proteins (e.g., DnaK, GroEL, and ClpB) was transiently induced upon temperature upshift from 25 to 37°C in the wild type, such induction was not observed in theΔrpoH mutant, except that GroEL synthesis was still partially induced. By contrast, theΔhrcA mutant grew normally and exhibited essentially normal heat induction except for a higher level of GroEL expression, especially before heat shock. TheΔrpoH ΔhrcA double mutant showed the combined phenotypes of each of the single mutants. The amounts ofdnaK andgroE transcripts before and after heat shock, as determined by primer extension, were consistent with those of the proteins synthesized. The cellular level of RpoH but not HrcA increased significantly upon heat shock. We conclude that RpoH plays a major and global role in the induction of most heat shock proteins, whereas HrcA plays a restricted role in repressinggroE expression under nonstress conditions.

journal of bacteriology

Differential and Independent Roles of a ς <sup>32</sup> Homolog (RpoH) and an HrcA Repressor in the Heat Shock Response of <i>Agrobacterium tumefaciens</i>

Differential and Independent Roles of a ς 32 Homolog (RpoH) and an HrcA Repressor in the Heat Shock Response of Agrobacterium tumefaciens

Differential and Independent Roles of a ς ³² Homolog (RpoH) and an HrcA Repressor in the Heat Shock Response of Agrobacterium tumefaciens