Structural basis for the cooperation of Hsp70 and Hsp110 chaperones in protein folding.
Protein folding by Hsp70 is tightly controlled by cochaperones, including J-domain proteins that trigger ATP hydrolysis and nucleotide exchange factors (NEFs) that remove ADP from Hsp70. Here we present the crystal structure of the yeast NEF Sse1p (Hsp110) in complex with the nucleotide-binding domain (NBD) of Hsp70. Hsp110 proteins are homologous to Hsp70s and consist of an NBD, a beta sandwich domain, and a three helix bundle domain (3HBD). In the complex, the NBD of Sse1p is ATP bound, and together with the 3HBD it embraces the NBD of Hsp70, inducing opening and the release of bound ADP from Hsp70. Mutations that abolish NEF activity are lethal, thus defining nucleotide exchange on Hsp70 as an essential function of Sse1p. Our data suggest that Sse1p does not employ the nucleotide-dependent allostery and peptide-binding mode of canonical Hsp70s, and that direct interactions of substrate with Sse1p may support Hsp70-assisted protein folding in a cooperative process.
Department of Cellular Biochemistry, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
Sigrun
S
Polier
Zdravko
Z
Dragovic
F Ulrich
FU
Hartl
Andreas
A
Bracher
D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D050957:HSP110 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D050884:HSP72 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; C090869:SSA3 protein, S cerevisiae; C494656:SSE1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins