Complete inhibition and partial Re-activation of single F1-ATPase molecules by tentoxin: new properties of the re-activated enzyme.
During hydrolysis of ATP, the gamma subunit of the rotary motor protein F(1)-ATPase rotates within a ring of alpha(3)beta(3) subunits. Tentoxin is a phyto-pathogenic cyclic tetrapeptide, which influences F(1)-ATPase activity of sensitive species. At low concentrations, tentoxin inhibits ATP hydrolysis of ensembles of F(1) molecules in solution. At higher concentrations, however, ATP hydrolysis recovers. Here we have examined how tentoxin acts on individual molecules of engineered F(1)-ATPase from the thermophilic Bacillus PS3 (Groth, G., Hisabori, T., Lill, H., and Bald, D. (2002) J. Biol. Chem. 277, 20117-20119). We found that inhibition by tentoxin caused a virtually complete stop of rotation, which was partially relieved at higher tentoxin concentrations. Re-activation, however, was not simply a reversal of inhibition; while the torque appears unaffected as compared with the situation without tentoxin, F(1) under re-activating conditions was less susceptible to inhibitory ADP binding but displayed a large number of short pauses, indicating infringed energy conversion.
Pavlova
Penka
P
Department of Structural Biology, Faculty of Earth and Life Science, Vrije Universiteit Amsterdam, The Netherlands.
Shimabukuro
Katsuya
K
Hisabori
Toru
T
Groth
Georg
G
Lill
Holger
H
Bald
Dirk
D
D025181:ATP Synthetase Complexes / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D025222:Chloroplast Proton-Translocating ATPases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D009154:Mutation; D010456:Peptides, Cyclic / Q000737:chemistry / Q000502:physiology*; D011485:Protein Binding; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
D010456:Peptides, Cyclic; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D025181:ATP Synthetase Complexes; D025222:Chloroplast Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; C003384:tentoxin