Molecular chaperones are proteins that assist the folding of other proteins. In stress conditions, they are crucial as proteins become misfolded. The Hsp90 chaperone is present in almost all living organisms and is essential in eukaryotes. In contrast, Hsp90 is dispensable in proteobacteria and few client proteins have been identified for bacterial Hsp90. Therefore, to uncover the role of Hsp90 in bacteria, new bacterial models are needed.
Bacteria from the Shewanellae genus are gamma-proteobacteria widely found in aquatic environments. Shewanellae have the astonishing ability to adapt to many stress conditions: large range of temperatures and salt concentrations, extremely high hydrostatic pressure since they can be found in deep-sea, and growth in very poor media. These environmental conditions being known to affect protein folding, it suggests the Shewanellae possess a large diversity of powerful chaperone proteins.
Our research aims to elucidate the function of Hsp90 in bacteria by using Shewanella oneidensis as a model organism. We first constructed an hsp90 deletion strain in S. oneidensis and found that in contrast to wild type, the mutated strain was unable to grow at high temperature. Taking advantage of this phenotype, we identified proteins that can suppress the absence of Hsp90 at high temperature by using a S. oneidensis library of plasmids. This genetic selection revealed several protein candidates that are currently under study. It is anticipated that our study using S. oneidensis as a new bacterial model will lead to a better understanding of the role of Hsp90 in bacteria.