Structural Analysis of Substrate Binding by the Molecular Chaperone DnaK

• Published in: Science (American Association for the Advancement of Science) 1996-06, Vol.272 (5268), p.1606-1614
• Main Authors: Zhu, Xiaotian, Zhao, Xun, Burkholder, William F., Gragerov, Alexander, Ogata, Craig M., Gottesman, Max E., Hendrickson, Wayne A.
• Format: Article
• Language: English
• Subjects: Active sites (Biochemistry); Adenosine triphosphatases; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Atoms; Binding and carrier proteins; Binding Sites; Binding sites (Biochemistry); Biochemistry; Biological and medical sciences; Chaperonins - chemistry; Chaperonins - metabolism; Crystallography, X-Ray; Crystals; Deoxyribonucleic acid; DNA; Escherichia coli; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Genetics; Heat shock proteins; HSP70 Heat-Shock Proteins - chemistry; HSP70 Heat-Shock Proteins - metabolism; Hydrogen bonds; Models, Molecular; Molecular biology; Molecular chaperones; Molecular Sequence Data; Molecules; Peptides - metabolism; Protein Binding; Protein Conformation; Proteins; Sandwiches; Sequence Homology, Amino Acid; Solvents; Structural Analysis (Linguistics); Structural Analysis (Science); Topology; Ungulates
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.272.5268.1606

DnaK and other members of the 70-kilodalton heat-shock protein (hsp70) family promote protein folding, interaction, and translocation, both constitutively and in response to stress, by binding to unfolded polypeptide segments. These proteins have two functional units: a substrate-binding portion binds the polypeptide, and an adenosine triphosphatase portion facilitates substrate exchange. The crystal structure of a peptide complex with the substrate-binding unit of DnaK has now been determined at 2.0 $\angst $ resolution. The structure consists of a β-sandwich subdomain followed by α-helical segments. The peptide is bound to DnaK in an extended conformation through a channel defined by loops from the β sandwich. An α-hellcal domain stabilizes the complex, but does not contact the peptide directly. This domain is rotated in the molecules of a second crystal lattice, which suggests a model of conformation-dependent substrate binding that features a latch mechanism for maintaining long lifetime complexes.