A zinc finger-like domain of the molecular chaperone DnaJ is involved in binding to denatured protein substrates.
The Escherichia coli heat-shock protein DnaJ cooperates with the Hsp70 homolog DnaK in protein folding in vitro and in vivo. Little is known about the structural features of DnaJ that mediate its interaction with DnaK and unfolded polypeptide. DnaJ contains at least four blocks of sequence representing potential functional domains which have been conserved throughout evolution. In order to understand the role of each of these regions, we have analyzed DnaJ fragments in reactions corresponding to known functions of the intact protein. Both the N-terminal 70 amino acid 'J-domain' and a 35 amino acid glycine-phenylalanine region following it are required for interactions with DnaK. However, only complete DnaJ can cooperate with DnaK and a third protein, GrpE, in refolding denatured firefly luciferase. As demonstrated by atomic absorption and extended X-ray absorption fine structure spectroscopy (EXAFS), the 90 amino acid cysteine-rich region of DnaJ contains two Zn atoms tetrahedrally coordinated to four cysteine residues, resembling their arrangement in the C4 Zn binding domains of certain DNA binding proteins. Interestingly, binding experiments and cross-linking studies indicate that this Zn finger-like domain is required for the DnaJ molecular chaperone to specifically recognize and bind to proteins in their denatured state.
Szabo
A
A
Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, 10021, USA.
Korszun
R
R
Hartl
F U
FU
Flanagan
J
J
D015502:Absorptiometry, Photon; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D016384:Consensus Sequence; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008156:Luciferases / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry / Q000378:metabolism; D016335:Zinc Fingers
D001426:Bacterial Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; D008156:Luciferases; D013884:Thiosulfate Sulfurtransferase; D000251:Adenosine Triphosphatases; C063842:dnaK protein, E coli