PMID: 25533486

Authors:

Galkin VE, Orlova A, Vos MR, Schroder GF, Egelman EH

Title:

Near-atomic resolution for one state of f-actin.

Journal:

Structure. 2015 Jan 6;23(1):173-82. doi: 10.1016/j.str.2014.11.006. Epub 2014 Dec, 18.

Abstract:

Actin functions as a helical polymer, F-actin, but attempts to build an atomic model for this filament have been hampered by the fact that the filament cannot be crystallized and by structural heterogeneity. We have used a direct electron detector, cryo-electron microscopy, and the forces imposed on actin filaments in thin films to reconstruct one state of the filament at 4.7 A resolution, which allows for building a reliable pseudo-atomic model of F-actin. We also report a different state of the filament where actin protomers adopt a conformation observed in the crystal structure of the G-actin-profilin complex with an open ATP-binding cleft. Comparison of the two structural states provides insights into ATP-hydrolysis and filament dynamics. The atomic model provides a framework for understanding why every buried residue in actin has been under intense selective pressure.