Examining kinesin processivity within a general gating framework

Version of Record: June 3, 2015
Accepted Manuscript: April 22, 2015

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Abstract

Kinesin-1 is a dimeric motor that transports cargo along microtubules, taking 8.2-nm steps in a hand-over-hand fashion. The ATP hydrolysis cycles of its two heads are maintained out of phase by a series of gating mechanisms, which lead to processive runs averaging ~1 μm. A key structural element for inter-head coordination is the neck linker (NL), which connects the heads to the stalk. To examine the role of the NL in regulating stepping, we investigated NL mutants of various lengths using single-molecule optical trapping and bulk fluorescence approaches in the context of a general framework for gating. Our results show that, although inter-head tension enhances motor velocity, it is crucial neither for inter-head coordination nor for rapid rear-head release. Furthermore, cysteine-light mutants do not produce wild-type motility under load. We conclude that kinesin-1 is primarily front-head gated, and that NL length is tuned to enhance unidirectional processivity and velocity.

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Johan O L Andreasson

Department of Genetics, Stanford University School of Medicine, Stanford University, Stanford, United States

Competing interests
The authors declare that no competing interests exist.
Bojan Milic

Biophysics Program, Stanford University, Stanford, United States

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The authors declare that no competing interests exist.
Geng-Yuan Chen

Department of Biomedical Engineering, Pennsylvania State University, University Park, United States

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The authors declare that no competing interests exist.
Nicholas R Guydosh

Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, United States

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The authors declare that no competing interests exist.
William O Hancock

Department of Biomedical Engineering, Pennsylvania State University, University Park, United States

Competing interests
The authors declare that no competing interests exist.
Steven M Block

Department of Biology, Stanford University, Stanford, United States

For correspondence
sblock@stanford.edu

Competing interests
The authors declare that no competing interests exist.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.