Bacterial Hsp90 mediates the degradation of aggregation-prone Hsp70-Hsp40 substrates preferentially by HslUV proteolysis

BioRxiv : the Preprint Server for Biology
Bruno FauvetPierre Goloubinoff

Abstract

Whereas in eukaryotic cells, the Hsp90s are profusely-studied molecular chaperones controlling protein homeostasis together with Hsp70s, in bacteria, the function of Hsp90 (HtpG) and its collaboration with Hsp70 (DnaK) remains unknown. To uncover physiological processes depending on HtpG and DnaK, we performed comparative quantitative proteomic analyses of insoluble and total protein fractions from unstressed wild type E. coli, and from knockout mutants ΔdnaKdnaJ (ΔKJ), ΔhtpG (ΔG) and ΔdnaKdnaJΔhtpG (ΔKJG) and compared their growth rates under heat-stress also with ΔdnaKdnaJΔhslV. Whereas, expectedly, mutant ΔG showed no proteomic differences with wild-type, ΔKJ expressed more chaperones, proteases and ribosomes and dramatically less metabolic and respiratory enzymes. Unexpectedly, we found that ΔKJG showed higher levels of metabolic and respiratory enzymes and both ΔKJG and ΔdnaKdnaJΔhslV grew better at 37°C than ΔKJ. The results indicate that bacterial Hsp90 mediates the degradation of aggregation-prone Hsp70-Hsp40 substrates, preferably by the HslUV protease.

Related Concepts

Bacterial Proteins
Escherichia coli
Peptide Hydrolases
Respiration Disorders
Ribosomes
HtpG protein, bacteria
Molecular Chaperones
Heat-Shock Proteins 70
HSP90 Heat-Shock Proteins
Heat-Shock Response

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