Evidence for the direct interaction between tightly bound divalent metal ion and ATP on actin. Binding of the lambda isomers of beta gamma-bidentate CrATP to actin.
Competition between Ca2+ and Mg2+ for binding to a single high affinity site on actin has been confirmed. Occupancy of this site only by either Ca2+ or Mg2+ affects the conformation of actin and its ability to form nuclei and hydrolyze ATP. G-actin binds the beta gamma-bidentate CrATP, a substitution inert analog of metal-ATP complexes, and shows a high specificity for the lambda isomers. Binding of CrATP to ADP-actin is accompanied by the dissociation of tightly bound ADP and Ca2+. CrATP-actin shows a high tendency to form nuclei, like MgATP-actin. Polymerization of CrATP-actin is accompanied by cleavage of the gamma-phosphate, but subsequent Pi release cannot occur because the product of the reaction is the stable CrADP-Pi complex. All these results support the view that the divalent metal ion tightly bound to actin interacts with the beta- and gamma-phosphates of ATP in the nucleotide site.
Valentin-Ranc
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C
Laboratoire d'Enzymologie, Centre National du Recherche Scientifique, Gif-sur-Yvette, France.
Carlier
M F
MF
D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000302:isolation & purification; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002857:Chromium / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D008433:Mathematics; D008962:Models, Theoretical; D009132:Muscles / Q000378:metabolism; D018272:Porins; D011485:Protein Binding; D011498:Protein Precursors / Q000235:genetics* / Q000302:isolation & purification; D011817:Rabbits
D000199:Actins; D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D011498:Protein Precursors; D002857:Chromium; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D008274:Magnesium; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium