TY - JOUR

T1 - A Unified Walking Model for Dimeric Motor Proteins

AU - Sasaki, Kazuo

AU - Kaya, Motoshi

AU - Higuchi, Hideo

N1 - Funding Information:
This study was supported by Grant-in-Aid for Scientific Research on Innovative Areas (H.H.; 23107002 ), Grant-in-Aid for Scientific Research (A) (H.H.; 23247022 ), Grant-in-Aid for Scientific Research (B) (K.S. and H.H.; 16H04773 ), Grant-in-Aid and for Scientific Research (C) (K.S.; 17K05562 ).

PY - 2018/11/20

Y1 - 2018/11/20

N2 - Dimeric motor proteins, kinesin-1, cytoplasmic dynein-1, and myosin-V, move stepwise along microtubules and actin filaments with a regular step size. The motors take backward as well as forward steps. The step ratio r and dwell time τ which are the ratio of the number of backward steps to the number of forward steps and the time between consecutive steps, respectively, were observed to change with the load. To understand the movement of motor proteins, we constructed a unified and simple mathematical model to explain the load dependencies of r and of τ measured for the above three types of motors quantitatively. Our model consists of three states, and the forward and backward steps are represented by the cycles of transitions visiting different pairs of states among the three, implying that a backward step is not the reversal of a forward step. Each of r and τ is given by a simple expression containing two exponential functions. The experimental data for r and τ for dynein available in the literature are not sufficient for a quantitative analysis, which is in contrast to those for kinesin and myosin-V. We reanalyze the data to obtain r and τ of native dynein to make up the insufficient data to fit them to the model. Our model successfully describes the behavior of r and τ for all of the motors in a wide range of loads from large assisting loads to superstall loads.

AB - Dimeric motor proteins, kinesin-1, cytoplasmic dynein-1, and myosin-V, move stepwise along microtubules and actin filaments with a regular step size. The motors take backward as well as forward steps. The step ratio r and dwell time τ which are the ratio of the number of backward steps to the number of forward steps and the time between consecutive steps, respectively, were observed to change with the load. To understand the movement of motor proteins, we constructed a unified and simple mathematical model to explain the load dependencies of r and of τ measured for the above three types of motors quantitatively. Our model consists of three states, and the forward and backward steps are represented by the cycles of transitions visiting different pairs of states among the three, implying that a backward step is not the reversal of a forward step. Each of r and τ is given by a simple expression containing two exponential functions. The experimental data for r and τ for dynein available in the literature are not sufficient for a quantitative analysis, which is in contrast to those for kinesin and myosin-V. We reanalyze the data to obtain r and τ of native dynein to make up the insufficient data to fit them to the model. Our model successfully describes the behavior of r and τ for all of the motors in a wide range of loads from large assisting loads to superstall loads.

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U2 - 10.1016/j.bpj.2018.09.032

DO - 10.1016/j.bpj.2018.09.032

M3 - Article

C2 - 30396511

AN - SCOPUS:85055913351

VL - 115

SP - 1981

EP - 1992

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 10

ER -