Gumiero, AndreaConz, CharlotteGesé, Genís ValentínZhang, YingWeyer, Felix AlexanderLapouge, KarineKappes, Juliavon Plehwe, UlrikeSchermann, GézaFitzke, EdithWölfle, TinaFischer, TamásRospert, SabineSinning, Irmgard2018-07-242018-07-242041-1723http://hdl.handle.net/1885/145287Cotranslational chaperones assist in de novo folding of nascent polypeptides in all organisms. In yeast, the heterodimeric ribosome-associated complex (RAC) forms a unique chaperone triad with the Hsp70 homologue Ssb. We report the X-ray structure of full length Ssb in the ATP-bound open conformation at 2.6 Å resolution and identify a positively charged region in the α-helical lid domain (SBDα), which is present in all members of the Ssb-subfamily of Hsp70s. Mutational analysis demonstrates that this region is strictly required for ribosome binding. Crosslinking shows that Ssb binds close to the tunnel exit via contacts with both, ribosomal proteins and rRNA, and that specific contacts can be correlated with switching between the open (ATP-bound) and closed (ADP-bound) conformation. Taken together, our data reveal how Ssb dynamics on the ribosome allows for the efficient interaction with nascent chains upon RAC-mediated activation of ATP hydrolysis.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) through FOR967 (to I.S. and S.R.), GRK1188 and the Leibniz programme (to I.S.), SFB 746 (to S.R.), and RO 1028/5-1 (to S.R.), and by HBIGS fellowships (to G.V.G. and F.A.W.), and by the Excellence Initiative of the German federal and state governments (BIOSS-2) (to S.R). I.S. is an investigator of the Cluster of Excellence: CellNetworks.12 pagesapplication/pdf© The Author(s) 2016. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/cotranslational chaperonespolypeptidesribosome-associated complex (RAC)Interaction of the cotranslational Hsp70 Ssb with ribosomal proteins and rRNA depends on its lid domain2016-11-2410.1038/ncomms13563