Reaction: (1) ATP + H2O + a folded polypeptide = ADP + phosphate + a partially unfolded polypeptide
(2) ATP + H2O + (polypeptide)n = ADP + phosphate + n polypeptide
Other name(s): molecular chaperone Hsc70 ATPase
Systematic name: ATP phosphohydrolase (polypeptide-unfolding)/depolymerizing
Comments: This is a highly diverse group of enzymes that perform many functions that are similar to those of chaperonins. They comprise a number of heat-shock-cognate proteins. They are also active in clathrin uncoating and in the oligomerization of actin. Chaperone binding to exposed hydrophobic segments in polypeptide substrates leads to an ATPase-dependent localized (minor) structural unfolding and a concomitant stabilization against misfolding and aggregation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Sadis, S. and Hightower, L.E. Unfolded proteins stimulate molecular chaperone Hsc70 ATPase by accelerating ADP/ATP exchange. Biochemistry 31 (1992) 9406-9412. [PMID: 1356434]
2. Blond-Elquindi, S., Fourie, A.M., Sambrook, J.F. and Gething, M.J. Peptide-dependent stimulation of the ATPase activity of the molecular chaperone BiP is the result of conversion of oligomers to active monomers. J. Biol. Chem. 268 (1993) 12730-12735. [PMID: 8509407]
3. Wawrzynow, A., Wojtkowiak, D., Marszalek, J., Banecki, B., Jonsen, M., Graves, B., Georgopoulos, C. and Zylicz, M. The ClpX heat-shock protein of Escherichia coli, the ATP-dependent substrate specificity component of the ClpP-ClpX protease, is a novel molecular chaperone. EMBO J. 14 (1995) 1867-1877. [PMID: 7743994]
4. Sriram, M., Osipiuk, J., Freeman, B., Morimoto, R. and Joachimiak, A. Human Hsp70 molecular chaperone binds two calcium ions within the ATPase domain. Structure 5 (1997) 403-414. [PMID: 9083109]
5. Finka, A., Mattoo, R.U. and Goloubinoff, P. Experimental milestones in the discovery of molecular chaperones as polypeptide unfolding enzymes. Annu. Rev. Biochem. 85 (2016) 715-742. [PMID: 27050154]