title: Theory of single-molecule controlled rotation experiments, predictions, tests, and comparison with stalling experiments in F1-ATPase.
abstract: A recently proposed chemomechanical group transfer theory of rotary biomolecular motors is applied to treat single-molecule controlled rotation experiments. In these experiments, single-molecule fluorescence is used to measure the binding and release rate constants of nucleotides by monitoring the occupancy of binding sites. It is shown how missed events of nucleotide binding and release in these experiments can be corrected using theory, with F1-ATP synthase as an example. The missed events are significant when the reverse rate is very fast. Using the theory the actual rate constants in the controlled rotation experiments and the corrections are predicted from independent data, including other single-molecule rotation and ensemble biochemical experiments. The effective torsional elastic constant is found to depend on the binding/releasing nucleotide, and it is smaller for ADP than for ATP. There is a good agreement, with no adjustable parameters, between the theoretical and experimental results of controlled rotation experiments and stalling experiments, for the range of angles where the data overlap. This agreement is perhaps all the more surprising because it occurs even though the binding and release of fluorescent nucleotides is monitored at single-site occupancy concentrations, whereas the stalling and free rotation experiments have multiple-site occupancy.
authors: Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125.
authors: Sándor
authors: S
authors: Volkán-Kacsó
authors: Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125 ram@caltech.edu.
authors: Rudolph A
authors: RA
authors: Marcus
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D001665:Binding Sites; D002232:Carbocyanines / Q000737:chemistry; D004548:Elasticity; D005456:Fluorescent Dyes / Q000737:chemistry; D006868:Hydrolysis; D017136:Ion Transport; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D012399:Rotation; D000072760:Single Molecule Imaging / Q000379:methods
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; C089187:cyanine dye 3; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases
keywords: F1-ATPase; biomolecular motors; group transfer theory; nucleotide binding; single-molecule imaging