title: ATPase domain of Hsp70 exhibits intrinsic ATP-ADP exchange activity.
abstract: The chaperone activity of Hsp70 in protein folding and its conformational switching are regulated through the hydrolysis of ATP and the ATP-ADP exchange cycle. It was reported that, in the presence of physiological concentrations of ATP (approximately 5 mM) and ADP (approximately 0.5 mM), Hsp70 catalyzes ATP-ADP exchange through transfer of gamma-phosphate between ATP and ADP, via an autophosphorylated intermediate, whereas it only catalyzes the hydrolysis of ATP in the absence of ADP. To clarify the functional domain of the ATP-ADP exchange activity of Hsp70, we isolated the 44-kD ATPase domain of Hsp70 after limited proteolysis with alpha-chymotrypsin (EC 3.4.21.1). The possibility of ATP-ADP exchange activity of a contaminating nucleoside diphosphate kinase (EC 2.7.4.6) was monitored throughout the experiments. The purified 44-kD ATPase domain exhibited intrinsic ATP-ADP exchange by catalyzing the transfer of gamma-phosphate between ATP and ADP with acid-stable autophosphorylation at Thr204.
authors.affiliation: Medical College, Xiamen University-National University of Singapore Laboratory of Biomedical Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Yubin
authors.initials: Y
authors.lastname: Mao
authors.forename: Aihua
authors.initials: A
authors.lastname: Deng
authors.forename: Ning
authors.initials: N
authors.lastname: Qu
authors.forename: Xueji
authors.initials: X
authors.lastname: Wu
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002918:Chymotrypsin / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary
chemical_list: D018840:HSP70 Heat-Shock Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009701:Nucleoside-Diphosphate Kinase; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D000251:Adenosine Triphosphatases