The F subunit of Thermus thermophilus V1-ATPase promotes ATPase activity but is not necessary for rotation
| Autor: | Ken Yokoyama, Hiromi Imamura, Masasuke Yoshida, Chiyo Ikeda |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Vacuolar Proton-Translocating ATPases
Time Factors Protein subunit Specificity factor Gi alpha subunit medicine.disease_cause Biochemistry Catalysis chemistry.chemical_compound Adenosine Triphosphate ATP hydrolysis ATP synthase gamma subunit medicine Escherichia coli Molecular Biology Adenosine Triphosphatases biology Dose-Response Relationship Drug Hydrolysis Thermus thermophilus Cell Biology DNA biology.organism_classification Molecular biology Protein Structure Tertiary Kinetics chemistry Mutation biology.protein Electrophoresis Polyacrylamide Gel Adenosine triphosphate Plasmids |
| Zdroj: | The Journal of biological chemistry. 279(17) |
| ISSN: | 0021-9258 |
| Popis: | V(1)-ATPase from the thermophilic bacterium Thermus thermophilus is a molecular rotary motor with a subunit composition of A(3)B(3)DF, and its central rotor is composed of the D and F subunits. To determine the role of the F subunit, we generated an A(3)B(3)D subcomplex and compared it with A(3)B(3)DF. The ATP hydrolyzing activity of A(3)B(3)D (V(max) = 20 s(-1)) was lower than that of A(3)B(3)DF (V(max) = 31 s(-1)) and was more susceptible to MgADP inhibition during ATP hydrolysis. A(3)B(3)D was able to bind the F subunit to form A(3)B(3)DF. The C-terminally truncated F((Delta85-106)) subunit was also bound to A(3)B(3)D, but the F((Delta69-106)) subunit was not, indicating the importance of residues 69-84 of the F subunit for association with A(3)B(3)D. The ATPase activity of A(3)B(3)DF((Delta85-106)) (V(max) = 24 s(-1)) was intermediate between that of A(3)B(3)D and A(3)B(3)DF. A single molecule experiment showed the rotation of the D subunit in A(3)B(3)D, implying that the F subunit is a dispensable component for rotation itself. Thus, the F subunit binds peripherally to the D subunit, but promotes V(1)-ATPase catalysis. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|