Abstract
A general kinetic model is presented for the chemomechanical coupling of dimeric kinesin molecular motors with and without extension of their neck linkers (NLs). A peculiar feature of the model is that the rate constants of ATPase activity of a kinesin head are independent of the strain on its NL, implying that the heads of the wild-type kinesin dimer and the mutant with extension of its NLs have the same force-independent rate constants of the ATPase activity. Based on the model, an analytical theory is presented on the force dependence of the dynamics of kinesin dimers with and without extension of their NLs at saturating ATP. With only a few adjustable parameters, diverse available single molecule data on the dynamics of various kinesin dimers, such as wild-type kinesin-1, kinesin-1 with mutated residues in the NLs, kinesin-1 with extension of the NLs and wild-type kinesin-2, under varying force and ATP concentration, can be reproduced very well. Additionally, we compare the power production among different kinesin dimers, showing that the mutation in the NLs reduces the power production and the extension of the NLs further reduces the power production.
Highlights
Motor proteins, called molecular motors, are important classes of macromolecules that play critical roles in supporting and maintaining various biological processes [1,2]
We first describe the model for the chemomechanical coupling pathway of kinesin dimer, based on which our theoretical analyses are made
A general kinetic model is presented for the chemomechanical coupling of kinesin dimers without and with extension of the neck linkers (NLs)
Summary
Called molecular motors, are important classes of macromolecules that play critical roles in supporting and maintaining various biological processes [1,2]. Among the kinesin superfamily [10], kinesin-1 and kinesin-2 motors are two typical families that have been studied extensively and intensively. An example of kinesin-2 motors is vertebrate KIF17 that is a homodimer but with the NL in each head having 17 residues [12]. Both families of kinesin dimers can move stepwise and progressively on MT filaments in a hand-over-hand manner and toward the plus end of MT in about 8.2 nm increments—the periodicity of an MT filament [13]. Important and interesting issues related to the motors are how the chemical reaction of ATPase activity couples with the mechanical stepping (i.e., the chemomechanical coupling) and their movement dynamics [14]
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