Polymerization of 70-kDa heat shock protein by yeast DnaJ in ATP.
DnaK, the Escherichia coli hsp70 protein, interacts with DnaJ, a protein cofactor that appears to be involved in presenting protein substrates to DnaK. The yeast DnaJ homolog, YDJ1, has also been shown to interact with yeast hsp70, although the function of this interaction is unknown. In the present study, we investigated the interaction of YDJ1 with both yeast and bovine brain hsp70. We found that, in the presence of ATP, where hsp70 is normally monomeric, YDJ1 induced almost all of the yeast and bovine brain hsp70 to form large polymers, which are readily sedimentable. These polymers were much larger than the dimers and trimers of hsp70, which normally form in the presence of ADP. YDJ1 appeared to be acting catalytically since very little YDJ1 copolymerized with the hsp70, and maximum polymerization occurred at low ratios of YDJ1 to hsp70. The polymerization required ATP and was completely reversed when ATP was replaced by ADP. These data suggest that, in the presence of ATP, YDJ1 may present one hsp70 to another just as under other conditions DnaJ is able to present protein substrates to DnaK.
King
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Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Eisenberg
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Greene
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D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D000091342:Endoplasmic Reticulum Chaperone BiP; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D018832:Molecular Chaperones / Q000378:metabolism; D011108:Polymers; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
D002352:Carrier Proteins; C494635:DnaJ protein, E coli; D000091342:Endoplasmic Reticulum Chaperone BiP; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011108:Polymers; D029701:Saccharomyces cerevisiae Proteins; C070319:YDJ1 protein, S cerevisiae; D000255:Adenosine Triphosphate