Science · 1996 · 1.3K citations · 55 references
Life SciencesBiochemistryMolecular BiologyEnzymologyProtein FoldingStructural BiologyChaperone-assisted FoldingChaperone-mediated FoldingMolecular ChaperonesProtein Complex AssemblyProtein StructureStable Protein ComplexesChaperone-mediated Folding PathwaysHelical ConformationHsp70 Chaperone SystemProtein Complex FoldingSandwich StructuresStress-induced Folding ResponsesStructural Biology Of ChaperonesSubstrate Binding Affinity
The 70‑kDa heat‑shock protein DnaK, like other Hsp70 family members, facilitates protein folding, interaction, and translocation by binding unfolded polypeptide segments through a substrate‑binding domain and an ATPase domain that mediates substrate exchange. The 2.0‑Å crystal structure of a peptide bound to DnaK’s substrate‑binding domain shows an extended peptide threaded through a loop‑defined channel in a β‑sandwich subdomain, with an α‑helical domain stabilizing the complex and rotating in a second lattice, supporting a latch‑like mechanism that prolongs substrate binding.
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 Å 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-helical 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.
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T. Alwyn Jones, Jin-yu Zou, Sandra W. Cowan et al. · Acta Crystallographica Section A Foundations of Crystallography · 1991 · 12.7K citations