Divergent functional properties of the ribosome-associated molecular chaperone Ssb compared with other Hsp70s.

ABSTRACT: Ssbs of Saccharomyces cerevisiae are ribosome-associated molecular chaperones, which can be cross-linked to nascent polypeptide chains. Because Ssbs are members of a divergent subclass of Hsp70s found thus far only in fungi, we asked if the structural requirements for in vivo function were similar to those of "classic" Hsp70s. An intact peptide-binding domain is essential and an alteration of a conserved residue in the peptide-binding cleft (V442) affects function. However, Ssb tolerates a number of alterations in the peptide-binding cleft, revealing a high degree of flexibility in its functional requirements. Because binding of Ssb to peptide substrates in vitro was undetectable, we assessed the importance of substrate binding using the chimera BAB, in which the peptide binding domain of

SUBMITTER: Pfund C 

PROVIDER: S-EPMC60754 | biostudies-literature | 2001 Dec

REPOSITORIES: biostudies-literature