title: Residues in chaperonin GroEL required for polypeptide binding and release.
abstract: Chaperonins are ring-shaped protein complexes that are essential in the cell, mediating ATP-dependent polypeptide folding in a variety of compartments. Recent studies suggest that they function through multiple rounds of binding and release of non-native proteins: with each round of ATP-driven release into the bulk solution, a substrate protein kinetically partitions between folding to the native state or rebinding to another chaperonin molecule. To gain further insight into the mechanism of polypeptide binding and release by the chaperonin GroEL from Escherichia coli, we have undertaken a mutational analysis that relates the functional properties of GroEL to its crystal structure. Our functional tests identify a putative polypeptide-binding site on the inside surface of the apical domain, facing the central channel, consisting of hydrophobic residues. These same residues are essential for binding of the co-chaperonin GroES, which is required for productive polypeptide release. A highly conserved residue, Asp 87, positioned within a putative nucleotide-binding pocket in the top of the equatorial domain, is essential for ATP hydrolysis and polypeptide release.
authors.affiliation: Department of Genetics, Yale University School of Medicine, Boyer Center, New Haven, Connecticut 06510.
authors.forename: W A
authors.initials: WA
authors.lastname: Fenton
authors.forename: Y
authors.initials: Y
authors.lastname: Kashi
authors.forename: K
authors.initials: K
authors.lastname: Furtak
authors.forename: A L
authors.initials: AL
authors.lastname: Horwich
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001665:Binding Sites; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D051381:Rats
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; D010455:Peptides; D001224:Aspartic Acid; D000255:Adenosine Triphosphate; D009954:Ornithine Carbamoyltransferase; D000251:Adenosine Triphosphatases