ATP synthesis and hydrolysis of the ATP-synthase from Micrococcus luteus regulated by an inhibitor subunit and membrane energization.
After incubation for 70 min in Tris-HCl (pH 8.0), the rate of ATP hydrolysis of free and reconstituted ATP-synthase from Micrococcus luteus multiplied about three times. The apparent increase in activity is due to the reversible dissociation of the delta-subunit. Results of experiments on the temperature dependence of the ATP hydrolysis rate of substrate saturated ATP-synthase exhibited a discontinuity in the Arrhenius plot at 32 +/- 0.5 degrees C for the delta-subunit associated enzyme. Below 32 +/- 0.5 degrees C the activation energy, Ea, was 231.5 +/- 5 kJ mol-1, while above this temperature-level it decreased to 76.4 +/- 3 kJ mol-1. ATP synthesis and hydrolysis of the ATP-synthase, co-reconstituted with monomeric bacteriorhodopsin (Halobacterium halobium), showed a lag of 50 s upon the illumination with green light (505-575 nm). This retardation and the activity depended on the ATP-synthase concentration, being typical of the dissociation of an inhibitor protein. The N-terminal protein sequences of the delta- and epsilon-subunit of the ATP-synthase were identified by automated Edman degradation. Alignment of the amino acid sequence and secondary structure calculations for the delta-subunit did not reveal homology to other known ATP-synthase delta-subunits, but significant equivalence to the epsilon-subunit of E. coli. Sequence analysis of the epsilon-subunit from M. luteus showed homology to equivalent regions in delta-subunits and Oligomycin Sensitivity Conferring Protein (OSCP) of other organisms.
Institute of Biochemistry, Joh. Gutenberg-University, Mainz, Germany.
G
G
Grüber
J
J
Godovac-Zimmermann
T
T
Nawroth
D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000595:Amino Acid Sequence; D001436:Bacteriorhodopsins / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism; D046911:Macromolecular Substances; D016982:Micrococcus luteus / Q000201:enzymology*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics
D008081:Liposomes; D046911:Macromolecular Substances; D001436:Bacteriorhodopsins; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases