title: Torque generation in F1-ATPase devoid of the entire amino-terminal helix of the rotor that fills half of the stator orifice.
abstract: F(1)-ATPase is an ATP-driven rotary molecular motor in which the central γ-subunit rotates inside a cylinder made of α(3)β(3) subunits. The amino and carboxyl termini of the γ rotor form a coiled coil of α-helices that penetrates the stator cylinder to serve as an axle. Crystal structures indicate that the axle is supported by the stator at two positions, at the orifice and by the hydrophobic sleeve surrounding the axle tip. The sleeve contacts are almost exclusively to the longer carboxyl-terminal helix, whereas nearly half the orifice contacts are to the amino-terminal helix. Here, we truncated the amino-terminal helix stepwise up to 50 residues, removing one half of the axle all the way up and far beyond the orifice. The half-sliced axle still rotated with an unloaded speed a quarter of the wild-type speed, with torque nearly half the wild-type torque. The truncations were made in a construct where the rotor tip was connected to a β-subunit via a short peptide linker. Linking alone did not change the rotational characteristics significantly. These and previous results show that nearly half the normal torque is generated if rotor-stator interactions either at the orifice or at the sleeve are preserved, suggesting that the make of the motor is quite robust.
authors: Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku,Tokyo, Japan.
authors: Ayako
authors: A
authors: Kohori
authors: Ryohei
authors: R
authors: Chiwata
authors: Mohammad Delawar
authors: MD
authors: Hossain
authors: Shou
authors: S
authors: Furuike
authors: Katsuyuki
authors: K
authors: Shiroguchi
authors: Kengo
authors: K
authors: Adachi
authors: Masasuke
authors: M
authors: Yoshida
authors: Kazuhiko
authors: K
authors: Kinosita
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D006046:Gold; D006868:Hydrolysis; D008863:Microspheres; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry; D010316:Particle Size; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D015203:Reproducibility of Results; D012399:Rotation; D019415:Torque
chemical_list: D050505:Mutant Proteins; D021122:Protein Subunits; D006046:Gold; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases