Lever Arm Mechanics of Processive MyosinsDawn A. Bonnell, University of Pennsylvania, DMR 0832802

NSECThree Unconventional Myosins

of Step Size is Related to Lever Arm Stiffness

Objectives:• Apply FIONA, polTIRF and Parallax to

ThreeUnconventional Myosins

• Determine Stepping Mechanics, Angles and Paths

• Compare Mechanics with Lever Arm Structures

Conclusions:• Lever arm stiffness among myosins V, VI and X are highly variable.• Step size is most variable in myosin VI and least variable in myosin V.• Sideways wobble is compatible with structures and implied stiffness.• Myosin structures are modulated to tune them for specialized functions.

Tilting Motions of Myosin V, VI and X

References:•Sun Y, Schroeder HW 3rd, Beausang JF, Homma K, Ikebe M, Goldman YE. Myosin VI walks "wiggly" on actin with large and variable tilting. Mol Cell. 2007 28:954-64.

• Sun Y, McKenna JD, Murray JM, Ostap EM, Goldman YE. Parallax: high accuracy three-dimensional single molecule tracking using split images. Nano Lett. 2009 9:2676-82.

•Sun Y, Sato O, Ruhnow F, Arsenault ME, Ikebe M, Goldman YE. Single-molecule stepping and structural dynamics of myosin X. Nat Struct Mol Biol. 2010 17:485-91.

•Sun Y, Goldman YE. Lever Arm Mechanics of Processive Myosins. Biophysical J. 2011, Provisionally accepted.