Peptide-dependent stimulation of the ATPase activity of the molecular chaperone BiP is the result of conversion of oligomers to active monomers.
The molecular chaperone BiP purified from bovine liver (bBiP) exhibits a low basal level of ATPase activity that can be stimulated 3-6-fold by synthetic peptides (Flynn, G. C., Chappell, T. G., and Rothman, J. E. (1989) Science 245, 385-390). By contrast, recombinant murine BiP (rBiP) purified to homogeneity following expression in Escherichia coli exhibits a higher basal level of ATPase activity and is much less stimulated by synthetic peptides. Nondenaturing gel electrophoresis showed that rBiP is predominantly monomeric, while bBiP exists in multiple forms probably corresponding to differentially modified monomeric, dimeric, and higher oligomeric species. Some, but not all, synthetic peptides cause conversion of the oligomeric and modified species of bBiP to a monomeric form. We propose that the peptide-dependent ATPase stimulation observed for BiP reflects the conversion of inactive oligomeric and/or modified species into active monomers.
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
S
S
Blond-Elguindi
A M
AM
Fourie
J F
JF
Sambrook
M J
MJ
Gething
D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D004274:DNA, Recombinant / Q000302:isolation & purification / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D000091342:Endoplasmic Reticulum Chaperone BiP; D004926:Escherichia coli / Q000235:genetics; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008954:Models, Biological; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism
D002352:Carrier Proteins; D004274:DNA, Recombinant; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases