Shaft Function of Kinesin-1's α4 Helix in the Processive Movement.
Cell Mol Bioeng 2019;
12:345-354. [PMID:
31719918 PMCID:
PMC6816713 DOI:
10.1007/s12195-019-00581-4]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022] Open
Abstract
INTRODUCTION
Kinesin-1 motor is a molecular walking machine constructed with amino acids. The understanding of how those structural elements play their mechanical roles is the key to the understanding of kinesin-1 mechanism.
METHODS
Using molecular dynamics simulations, we investigate the role of a helix structure, α4 (also called switch-II helix), of kinesin-1's motor domain in its processive movement along microtubule.
RESULTS
Through the analysis of the structure and the interactions between α4 and the surrounding residues in different nucleotide-binding states, we find that, mechanically, this helix functions as a shaft for kinesin-1's motor-domain rotation and, structurally, it is an amphipathic helix ensuring its shaft functioning. The hydrophobic side of α4 consists strictly of hydrophobic residues, making it behave like a lubricated surface in contact with the core β-sheet of kinesin-1's motor domain. The opposite hydrophilic side of α4 leans firmly against microtubule with charged residues locating at both ends to facilitate its positioning onto the intra-tubulin groove.
CONCLUSIONS
The special structural feature of α4 makes for an effective reduction of the conformational work in kinesin-1's force generation process.
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