Yeast cytoplasmic dynein (CD) motor proteins walk processively along a microtubule (MT). What path does CD move along a MT? To address this question, we developed three-dimensional tracking assay which allowed the CD-coated beads to move freely along and around the MT anchored on an etched glass as a suspension bridge, unhindered by glass surface. Observing movement of the CD-coated beads among all surfaces of the suspended MT, we found that the CD-coated beads moved laterally toward both the

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... ght and the left, when it moves toward the minus end of the MT. Our analysis showed that CD does not follow the MT's protofilament (Pf) axis, but that CD takes a route switching randomly between Pfs with a bias toward the right, inducing the mainly right-handed corkscrew path. 1P152 細菌べん毛モーター固定子複合体のイオン透過メカニズム Ion permeation mechanism through the stator complex in the flagellar motor Bacterial flagellar motors are powered by ions (protons in Escherichia coli and sodium ions in Vibrio alginolyticus). The motor consists of a rotor and stators. The stator acts as a torque generation unit and comprises MotA and MotB protein in E. coli or PomA and PomB protein in V. alginolyticus. However the molecular mechanism for torque generation is still unclear. To investigate the structural changes coupled with ion permeation through the stator, we performed molecular dynamics calculations with our model structures. Our results showed that the movements of helices in MotA and MotB were induced by ion permeation. We will also discuss the difference between the helix movements of MotA/MotB and PomA/PomB. 1P153 V1 モーターでのトルク発生機構 The V1 rotary ATPases contain a rotor that rotates against a catalytic A3B3 stator. The rotor V1-DF is composed of both anti-parallel coiled coil and globular-loop parts. Single molecular analysis indicates that an anti-parallel coiled-coil domain of V1-D functions as a rotor in A3B3. Contrary, FliJ protein from flagellar, also composed of an anti-parallel coiled-coil, did not show the unidirectional rotation. In this study, we report the essential region of D subunit for unidirectional rotation by a domain swapping approach. 1P154 LC1 Binds to the Stalk of the Outer Arm Dynein Outer arm dynein (OAD) complex drives beating of flagella/cilia. OAD complex is composed of three heavy chains (α, β, γ HCs), intermediate chains (ICs), and light chains (LCs), but the exact subunit architecture has not been elucidated. LC1 is a 22-kDa light chain and widely preserved among many species. To directly label the LC1 in ODA complex, we expressed recombinant Histagged LC1 in Tetrahymena and Chlamydomonas. By electron microscopy aided by Ni-NTA-gold labeling, LC1 was found at the γ-stalk (Chlamydomonas), unlike the previous assumption that LC1 bound at the γ-head. Pull-down assay revealed that LC1 preferentially binds to γ-stalk at 1:1 molar ratio. These results raise the possibility that LC1 regulates OAD activity by changing its affinity to microtubules. Dyneins are large microtubule motor proteins. ADP-bound high-resolution structures have revealed the organization of the dynein motor domain which comprises the AAA+ ring, the linker, stalk/strut and C sequence. However, a high-resolution ATP-bound dynein conformer remains unclear. We modeled the ATP-bound form, and carried out a 200-ns molecular dynamics simulation for both ADP-and ATP-bound forms using our psygene-G program to investigate the effect of ATP on the structure and dynamics. The stalk of the ATP-bound form was more flexible than that of the ADP-bound form. Two additional 50-ns simulations starting from the ADP-bound form with ATP ligand reproduced this flexibility. The rigidness of both obtained trajectories qualitatively agrees with experimental results. 1P156 細菌Ⅲ型分泌装置の回転運動およびエフェクター分泌に対す る高粘性高分子の物理化学的影響評価 Evaluation of physicochemical effect of viscous polymers toward rotation and effector secretion of bacterial type III secretion apparatus