The 1.6-A crystal structure of the class of chaperones represented by Escherichia coli Hsp31 reveals a putative catalytic triad.
Heat shock proteins (Hsps) play essential protective roles under stress conditions by preventing the formation of protein aggregates and degrading misfolded proteins. EcHsp31, the yedU (hchA) gene product, is a representative member of a family of chaperones that alleviates protein misfolding by interacting with early unfolding intermediates. The 1.6-A crystal structure of the EcHsp31 dimer reveals a system of hydrophobic patches, canyons, and grooves, which may stabilize partially unfolded substrate. The presence of a well conserved, yet buried, triad in each two-domain subunit suggests a still unproven hydrolytic function of the protein. A flexible extended linker between the A and P domains may play a role in conformational flexibility and substrate binding. The alpha-beta sandwich of the EcHsp31 monomer shows structural similarity to PhPI, a protease belonging to the DJ-1 superfamily. The structure-guided sequence alignment indicates that Hsp31 homologs can be divided in three classes based on variations in the P domain that dramatically affect both oligomerization and catalytic triad formation.
Quigley
Paulene M
PM
Biomolecular Structure Center, P.O. Box 357742, University of Washington, Seattle, WA 98195, USA. paulene@u.washington.edu
Korotkov
Konstantin
K
Baneyx
Francois
F
Hol
Wim G J
WG
D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D019711:Pyrococcus / Q000201:enzymology / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D021122:Protein Subunits; C469996:hchA protein, E coli; D010450:Endopeptidases