The structure of ClpB: a molecular chaperone that rescues proteins from an aggregated state.
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 A 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.
Lee
Sukyeong
S
Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Sowa
Mathew E
ME
Watanabe
Yo-hei
YH
Sigler
Paul B
PB
Chiu
Wah
W
Yoshida
Masasuke
M
Tsai
Francis T F
FT
D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus
D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D000255:Adenosine Triphosphate