The crystal structure of the reduced, Zn2+-bound form of the B. subtilis Hsp33 chaperone and its implications for the activation mechanism.
The bacterial heat shock protein Hsp33 is a redox-regulated chaperone activated by oxidative stress. In response to oxidation, four cysteines within a Zn2+ binding C-terminal domain form two disulfide bonds with concomitant release of the metal. This leads to the formation of the biologically active Hsp33 dimer. The crystal structure of the N-terminal domain of the E. coli protein has been reported, but neither the structure of the Zn2+ binding motif nor the nature of its regulatory interaction with the rest of the protein are known. Here we report the crystal structure of the full-length B. subtilis Hsp33 in the reduced form. The structure of the N-terminal, dimerization domain is similar to that of the E. coli protein, although there is no domain swapping. The Zn2+ binding domain is clearly resolved showing the details of the tetrahedral coordination of Zn2+ by four thiolates. We propose a structure-based activation pathway for Hsp33.
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
Izabela
I
Janda
Yancho
Y
Devedjiev
Urszula
U
Derewenda
Zbigniew
Z
Dauter
Jakub
J
Bielnicki
David R
DR
Cooper
Paul C F
PC
Graf
Andrzej
A
Joachimiak
Ursula
U
Jakob
Zygmunt S
ZS
Derewenda
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003461:Crystallography; D019281:Dimerization; D019277:Entropy; D029968:Escherichia coli Proteins / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D015032:Zinc