Physiological ligands ADP and Pi modulate the degree of intrinsic coupling in the ATP synthase of the photosynthetic bacterium Rhodobacter capsulatus

Biochemistry. 2004 Aug 31;43(34):11126-34. doi: 10.1021/bi048975+.

Abstract

The proton-pumping and the ATP hydrolysis activities of the ATP synthase of Rhodobacter capsulatus have been compared as a function of the ADP and P(i) concentrations. The proton pumping was measured either with the transmembrane pH difference probe, 9-amino-6-chloro-2-methoxyacridine, or with the transmembrane electric potential difference probe, bis(3-propyl-5-oxoisoxazol-4-yl)pentamethine oxonol, obtaining consistent results. The comparison indicates that an intrinsic uncoupling of ATP synthase is induced when the concentration of either ligand is decreased. The half-maximal effect was found in the submicromolar range for ADP and at about 70 microM for P(i). It is proposed that a switch from a partially uncoupled state of ATP synthase to the coupled state is induced by the simultaneous binding of ADP and P(i).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / chemistry
  • Adenosine Diphosphate / metabolism
  • Adenosine Diphosphate / physiology*
  • Adenosine Triphosphate / metabolism
  • Aminoacridines / metabolism
  • Binding Sites
  • Chloroplast Proton-Translocating ATPases / chemistry
  • Chloroplast Proton-Translocating ATPases / metabolism*
  • Cytoplasmic Vesicles / enzymology
  • Hydrolysis
  • Isoxazoles / metabolism
  • Ligands
  • Osmosis
  • Phosphates / chemistry
  • Phosphates / metabolism
  • Phosphates / physiology*
  • Photosynthesis*
  • Pyruvate Kinase / metabolism
  • Rhodobacter capsulatus / enzymology*
  • Rhodobacter capsulatus / growth & development

Substances

  • Aminoacridines
  • Isoxazoles
  • Ligands
  • Phosphates
  • 9-amino-6-chloro-2-methoxyacridine
  • Adenosine Diphosphate
  • oxonol VI
  • Adenosine Triphosphate
  • Pyruvate Kinase
  • Chloroplast Proton-Translocating ATPases