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Engineering Approaches to Biomolecular Motors: From in vitro to in vivo Poster Abstracts

52

27-POS

Board 27

Forestep-Backstep Ratio Determines Stall Force for both Fast and Slow Kinesin-1

Algirdas Toleikis

, Nicholas J. Carter, Robert A. Cross.

University of Warwick, Coventry, United Kingdom.

Kinesin-1 is a motor protein responsible for molecular transport inside cells. It consumes ATP as

an energy source required to do work and transports cargos while walking on microtubule tracks.

Kinesin-1 is a processive motor and can walk ~100 steps before falling off. It walks in ~8 nm

steps in a hand-over-hand fashion and stalls at ~7 pN backwards (hindering) force. At this stall

force, steps are infrequent so backstepping and forward stepping are equally probable. In this

work, we are using optical trapping to apply directional force on single kinesins in vitro to study

the mechanism of stepping. Particularly, we are focusing on the directionality of stepping,

counting forward vs backward steps at a particular force, and interrogating the mechanism

underlying the switch of direction. We are comparing kinesin-1 isoforms from Drosophilla and

Neurospora to better understand how nature has engineered changes in amino acid sequence that

influence the stepping behaviour. We present preliminary data which we hope in the future might

help us understand the mechanistic determinants of stepping directionality.