An essential regulatory function of the DnaK chaperone dictates the decision between proliferation and maintenance in Caulobacter crescentus.

ABSTRACT: Hsp70 chaperones are well known for their important functions in maintaining protein homeostasis during thermal stress conditions. In many bacteria the Hsp70 homolog DnaK is also required for growth in the absence of stress. The molecular reasons underlying Hsp70 essentiality remain in most cases unclear. Here, we demonstrate that DnaK is essential in the α-proteobacterium Caulobacter crescentus due to its regulatory function in gene expression. Using a suppressor screen we identified mutations that allow growth in the absence of DnaK. All mutations reduced the activity of the heat shock sigma factor σ32, demonstrating that the DnaK-dependent inactivation of σ32 is a growth requirement. While most mutations occurred in the rpoH gene encoding σ32, we also identified mutations affecting σ32

SUBMITTER: Schramm FD 

PROVIDER: S-EPMC5760092 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature