Crystal structure of the C-terminal 10-kDa subdomain of Hsc70.
The 70-kDa heat shock proteins (Hsp70), including the cognates (Hsc70), are molecular chaperones that prevent misfolding and aggregation of polypeptides in cells under both normal and stressed conditions. They are composed of two major structural domains: an N-terminal 44-kDa ATPase domain and a C-terminal 30-kDa substrate binding domain. The 30-kDa domain can be divided into an 18-kDa subdomain and a 10-kDa subdomain. Here we report the crystal structure of the 10-kDa subdomain of rat Hsc70 at 3.45 A. Its helical region adopted a helix-loop-helix fold. This conformation is different from the equivalent subdomain of DnaK, the bacterial homologue of Hsc70. Moreover, in the crystalline state, the 10-kDa subdomain formed dimers. The results of gel filtration chromatography further supported the view that this subdomain was self-associated. Upon gel filtration, Hsc70 was found to exist as a mixture of monomers, dimers, and oligomers, but the 60-kDa fragment was predominantly found to exist as monomers. These findings suggest that the alpha-helical region of the 10-kDa subdomain dictates the chaperone self-association.
Chou
Chia-Cheng
CC
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China.
Forouhar
Farhad
F
Yeh
Yi-Hong
YH
Shr
Hui-Lin
HL
Wang
Chung
C
Hsiao
Chwan-Deng
CD
D000595:Amino Acid Sequence; D000818:Animals; D002845:Chromatography; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D017386:Sequence Homology, Amino Acid
D029968:Escherichia coli Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494373:Hspa8 protein, rat; C063842:dnaK protein, E coli