The characteristics of the (alpha V371C)3(beta R337C)3 gamma double mutant subcomplex of the TF1-ATPase indicate that the catalytic site at the alpha TP-beta TP interface with bound MgADP in crystal structures of MF1 represents a catalytic site containing inhibitory MgADP.
In the MF(1) crystal structure with the MgADP-fluoroaluminate complex bound to two catalytic sites [Menz, R. I., Walker, J. E., and Leslie, A. G. W. (2001) Cell 106, 331-341], the guanidinium of betaR(337) is within 2.9 A of the alpha-oxygen of alphaS(370) and 3.7 A of a methyl group of alphaV(371) at the alpha(E)-beta(HC) interface. To examine the functional role of this contact, the (alphaV(371)C)(3)(betaR(337)C)(3)gamma subcomplex of the TF(1)-ATPase was prepared and characterized. Steady state ATPase activity of the reduced double-mutant is 30% of that of the wild type. Inactivation of the double mutant containing empty catalytic sites or MgADP bound to one catalytic site with CuCl(2) cross-linked two alpha-beta pairs, whereas a single alpha-beta pair cross-linked when at least two catalytic sites contained MgADP. The reduced double mutant hydrolyzed substoichiometric ATP 100-fold more rapidly than the enzyme containing two cross-linked alpha-beta pairs. Addition of AlCl(3) and NaF to the reduced double mutant after incubation with stoichiometric MgADP or 200 microM MgADP irreversibly inactivated the steady state ATPase activity with rate constants of 1.5 x10(-2) and 4.1 x 10(-2) min(-1), respectively. In contrast, addition of AlCl(3) and NaF to the cross-linked enzyme after incubation with stoichiometric or 200 microM MgADP irreversibly inactivated ATPase activity with a common rate constant of approximately 10(-4) min(-1). Correlation of these results with crystal structures of MF(1) suggests that the catalytic site at the alpha(TP)-beta(TP) interface is loaded first upon addition of nucleotides to nucleotide-depleted F(1)-ATPases and that the catalytic site at the alpha(TP)-beta(TP) interface with bound MgADP in crystal structures represents a catalytic site containing inhibitory MgADP.
Bandyopadhyay
Sanjay
S
Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0601, USA.
Muneyuki
Eiro
E
Allison
William S
WS
D000244:Adenosine Diphosphate / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism; D000535:Aluminum / Q000737:chemistry; D000818:Animals; D001120:Arginine / Q000235:genetics; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics*; D002417:Cattle; D003300:Copper / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism; D003460:Crystallization; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry; D006868:Hydrolysis; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D021122:Protein Subunits / Q000235:genetics*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D013499:Surface Properties; D014633:Valine / Q000235:genetics
D003432:Cross-Linking Reagents; D004791:Enzyme Inhibitors; D021122:Protein Subunits; C053629:fluoroaluminum; D005461:Fluorine; D000244:Adenosine Diphosphate; D003300:Copper; D000255:Adenosine Triphosphate; D001120:Arginine; D000535:Aluminum; D006180:Proton-Translocating ATPases; D014633:Valine; D003545:Cysteine; C029892:cupric chloride