title: Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor.
abstract: The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a high duty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins.
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany;
authors.forename: Ralph P
authors.initials: RP
authors.lastname: Diensthuber
authors.affiliation: Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan; Science and Technology Agency, PRESTO, Saitama, Japan;
authors.forename: Motoki
authors.initials: M
authors.lastname: Tominaga
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany; Centre for Structural Systems Biology, German Electron Synchrotron (DESY), Hamburg, Germany;
authors.forename: Matthias
authors.initials: M
authors.lastname: Preller
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany;
authors.forename: Falk K
authors.initials: FK
authors.lastname: Hartmann
authors.affiliation: Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Orii
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany;
authors.forename: Igor
authors.initials: I
authors.lastname: Chizhov
authors.affiliation: Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oiwa
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany; tsiavaliaris.georgios@mh-hannover.de.
authors.forename: Georgios
authors.initials: G
authors.lastname: Tsiavaliaris
mesh_terms: D000199:Actins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009218:Myosins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D020409:Molecular Motor Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009218:Myosins
keywords: homology modeling; molecular mechanics; plant; processivity