Co-translational folding of nascent polypeptides is essential for maintaining a functional and healthy proteome in all cells. Ribosome-associated chaperones bind to nascent chains after they emerge from the peptide exit tunnel (PET) on the 60S subunit to facilitate their de novo folding. There are two types of co-translational chaperones in eukaryotes, the nascent-polypeptide associated complex (NAC) and the ribosome-associated complex (RAC). The composition of RAC as a heterodimer is conserved from yeast to human, with two tightly associated HSP40 (Zuo1 in yeast, ZRF1/MPP11/MIDA1 in mammals) and HSP70 (Ssz1 in yeast, HSP70L1/HSPA14 in mammals) components. The co-translational role of the RAC-HSP70 system is well characterized in fungal systems. In fast growing cells of Saccharomyces cerevisiae, most RACs are ribosome-bound, and the ribosome attachment is mediated by Zuo1. Absence of any components in the Zuo1-Ssz1-Ssb triad induced similar phenotypes, such as growth defects and high sensitivity to cold, salt and aminoglycosides. Here you can see a recent Cryo-EM structure of RNC-RAC complex in presence of Ssb from Saccharomyces cereviseae (PDB code: 7X34)
#molecularart ... #immolecular ... #translation ... #ribosome ... #yeast ... #folding ... #cryoem
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #translation ... #ribosome ... #yeast ... #folding ... #cryoem
Structure rendered with @proteinimaging and depicted with @corelphotopaint
