7X3K

Cryo-EM structure of RAC in the State C2 RNC-RAC complex

Summary for 7X3K

• Entry DOI: 10.2210/pdb7x3k/pdb
• EMDB information: 32988 32991
• Descriptor: Zuotin, Ribosome-associated complex subunit SSZ1 (2 entities in total)
• Functional Keywords: rac, co-translational folding, translation
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Total number of polymer chains: 2
• Total formula weight: 107410.52

Authors

Chen, Y.,Gao, N. (deposition date: 2022-03-01, release date: 2022-06-29, Last modification date: 2024-06-26)

Primary citation

Chen, Y.,Tsai, B.,Li, N.,Gao, N.
Structural remodeling of ribosome associated Hsp40-Hsp70 chaperones during co-translational folding.
Nat Commun, 13:3410-3410, 2022

PubMed Abstract: Ribosome associated complex (RAC), an obligate heterodimer of HSP40 and HSP70 (Zuo1 and Ssz1 in yeast), is conserved in eukaryotes and functions as co-chaperone for another HSP70 (Ssb1/2 in yeast) to facilitate co-translational folding of nascent polypeptides. Many mechanistic details, such as the coordination of one HSP40 with two HSP70s and the dynamic interplay between RAC-Ssb and growing nascent chains, remain unclear. Here, we report three sets of structures of RAC-containing ribosomal complexes isolated from Saccharomyces cerevisiae. Structural analyses indicate that RAC on the nascent-chain-free ribosome is in an autoinhibited conformation, and in the presence of a nascent chain at the peptide tunnel exit (PTE), RAC undergoes large-scale structural remodeling to make Zuo1 J-Domain more accessible to Ssb. Our data also suggest a role of Zuo1 in orienting Ssb-SBD proximal to the PTE for easy capture of the substrate. Altogether, in accordance with previous data, our work suggests a sequence of structural remodeling events for RAC-Ssb during co-translational folding, triggered by the binding and passage of growing nascent chain from one to another.

PubMed: 35701497
DOI: 10.1038/s41467-022-31127-4

Experimental method

ELECTRON MICROSCOPY (6 Å)