Crystallographic anomalous scattering from potassium at 1.7 A resolution reveals two monovalent ions that interact with MgADP and P(i) in the nucleotide binding cleft of wild-type recombinant bovine Hsc70 ATPase fragment. K+ at site 1 interacts with oxygens of the beta-phosphate of ADP, whereas K+ at site 2 interacts with an oxygen of P(i). Both K+ ions also interact with specific H2O molecules in the first hydration shell of the octahedrally coordinated Mg2+ ion and with specific protein ligands. In crystals that have Na+ present, K+ is replaced by a Na+ ion at site 1 and by a Na(+)-H2O pair at site 2. The K+ ions are positioned where they could stabilize binding of a beta,gamma-bidentate MgATP complex with Hsc70, as well as a transition state during ATP hydrolysis, suggesting that monovalent ions act as specific metal cofactors in the ATPase reaction of Hsc70.
How potassium affects the activity of the molecular chaperone Hsc70. II. Potassium binds specifically in the ATPase active site.,Wilbanks SM, McKay DB J Biol Chem. 1995 Feb 3;270(5):2251-7. PMID:7836458
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Wilbanks SM, McKay DB. How potassium affects the activity of the molecular chaperone Hsc70. II. Potassium binds specifically in the ATPase active site. J Biol Chem. 1995 Feb 3;270(5):2251-7. PMID:7836458