Chaperones are essential for the maintenance of cellular protein homeostasis, and although heat shock protein 90 (Hsp90) is one of the best-characterized chaperones in eukaryotes, its role in bacteria has remained elusive. Honoré et al. report that a Shewanella oneidensis strain that lacks hsp90 exhibits a growth defect at high temperatures compared with the wild-type strain. By screening a plasmid library, they identified its first client as TilS, a protein that is involved in tRNA maturation. Moreover, in vivo bacterial two-hybrid assay and pull-down experiments revealed that the two proteins directly interact. The aggregation of TilS at high temperatures was markedly decreased in presence of Hsp90, further corroborating the crucial role of the chaperone in folding. As Hsp90 is highly conserved in bacteria, the authors speculate that it might have a similar role in other bacteria. Further work is required to address this question and identify other possible clients.