The Structure of ClpB: A Molecular Chaperone that Rescues Proteins from an Aggregated State

• Published in: Cell 2003-10, Vol.115 (2), p.229-240
• Main Authors: Lee, Sukyeong, Sowa, Mathew E, Watanabe, Yo-hei, Sigler, Paul B, Chiu, Wah, Yoshida, Masasuke, Tsai, Francis T.F
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Motifs; Amino Acid Sequence; BASIC BIOLOGICAL SCIENCES; BIOLOGY; BNL; ClpB protein; Cryoelectron Microscopy; Crystallography, X-Ray; Heat-Shock Proteins - chemistry; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Hsp104 protein; Models, Biological; Models, Molecular; Molecular Chaperones - chemistry; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Molecular Sequence Data; Molecular Weight; Mutagenesis, Site-Directed; NATIONAL SYNCHROTRON LIGHT SOURCE; Protein Conformation; Protein Denaturation; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; PROTEINS; Sequence Homology, Amino Acid; Thermus thermophilus
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(03)00807-9

Molecular chaperones assist protein folding by facilitating their “forward” folding and preventing aggregation. However, once aggregates have formed, these chaperones cannot facilitate protein disaggregation. Bacterial ClpB and its eukaryotic homolog Hsp104 are essential proteins of the heat-shock response, which have the remarkable capacity to rescue stress-damaged proteins from an aggregated state. We have determined the structure of Thermus thermophilus ClpB ( TClpB) using a combination of X-ray crystallography and cryo-electron microscopy (cryo-EM). Our single-particle reconstruction shows that TClpB forms a two-tiered hexameric ring. The ClpB/Hsp104-linker consists of an 85 Å long and mobile coiled coil that is located on the outside of the hexamer. Our mutagenesis and biochemical data show that both the relative position and motion of this coiled coil are critical for chaperone function. Taken together, we propose a mechanism by which an ATP-driven conformational change is coupled to a large coiled-coil motion, which is indispensable for protein disaggregation.