Met23Lys mutation in subunit gamma of F(O)F(1)-ATP synthase from Rhodobacter capsulatus impairs the activation of ATP hydrolysis by protonmotive force.
H(+)-F(O)F(1)-ATP synthase couples proton flow through its membrane portion, F(O), to the synthesis of ATP in its headpiece, F(1). Upon reversal of the reaction the enzyme functions as a proton pumping ATPase. Even in the simplest bacterial enzyme the ATPase activity is regulated by several mechanisms, involving inhibition by MgADP, conformational transitions of the epsilon subunit, and activation by protonmotive force. Here we report that the Met23Lys mutation in the gamma subunit of the Rhodobacter capsulatus ATP synthase significantly impaired the activation of ATP hydrolysis by protonmotive force. The impairment in the mutant was due to faster enzyme deactivation that was particularly evident at low ATP/ADP ratio. We suggest that the electrostatic interaction of the introduced gammaLys23 with the DELSEED region of subunit beta stabilized the ADP-inhibited state of the enzyme by hindering the rotation of subunit gamma rotation which is necessary for the activation.
Feniouk
Boris A
BA
Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, D-49069, Osnabrück, Germany. feniouk@atp.miraikan.jst.go.jp
Rebecchi
Alberto
A
Giovannini
Donatella
D
Anefors
Sofie
S
Mulkidjanian
Armen Y
AY
Junge
Wolfgang
W
Turina
Paola
P
Melandri
B Andrea
BA
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D019943:Amino Acid Substitution; D025243:Bacterial Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D009154:Mutation; D010084:Oxidation-Reduction; D017494:Proton Pumps / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018892:Proton-Motive Force; D011522:Protons; D011770:Pyruvate Kinase / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics
D017494:Proton Pumps; D011522:Protons; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D025243:Bacterial Proton-Translocating ATPases