Reversible inhibition of Hsp70 chaperone function by Scythe and Reaper.
Protein folding mediated by the Hsp70 family of molecular chaperones requires both ATP and the co-chaperone Hdj-1. BAG-1 was recently identified as a bcl-2-interacting, anti-apoptotic protein that binds to the ATPase domain of Hsp70 and prevents the release of the substrate. While this suggested that cells had the potential to modulate Hsp70-mediated protein folding, physiological regulators of BAG-1 have yet to be identified. We report here that the apoptotic regulator Scythe, originally isolated through binding to the potent apoptotic inducer Reaper, shares limited sequence identity with BAG-1 and inhibits Hsp70- mediated protein refolding. Scythe-mediated inhibition of Hsp70 is reversed by Reaper, providing evidence for the regulated reversible inhibition of chaperone activity. As Scythe functions downstream of Reaper in apoptotic induction, these findings suggest that Scythe/Reaper may signal apoptosis, in part through regulating the folding and activity of apoptotic signaling molecules.
Thress
K
K
Department of Pharmacology and Cancer Biology, C370 LSRC, Research Drive, Duke University Medical Center, Durham, NC 27710, USA.
Song
J
J
Morimoto
R I
RI
Kornbluth
S
S
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000737:chemistry; D003574:Cytochrome c Group / Q000378:metabolism; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors; D014981:Xenopus; D029867:Xenopus Proteins
C116358:BAG6 protein, Xenopus; C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D003574:Cytochrome c Group; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D010455:Peptides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C086973:rpr protein, Drosophila; D000251:Adenosine Triphosphatases