PMID: 28602822

Authors:

Lane TR, Fuchs E, Slep KC

Title:

Structure of the ACF7 EF-Hand-GAR Module and Delineation of Microtubule Binding Determinants.

Journal:

Structure. 2017 Jul 5;25(7):1130-1138.e6. doi: 10.1016/j.str.2017.05.006. Epub, 2017 Jun 8.

Abstract:

Spectraplakins are large molecules that cross-link F-actin and microtubules (MTs). Mutations in spectraplakins yield defective cell polarization, aberrant focal adhesion dynamics, and dystonia. We present the 2.8 A crystal structure of the hACF7 EF1-EF2-GAR MT-binding module and delineate the GAR residues critical for MT binding. The EF1-EF2 and GAR domains are autonomous domains connected by a flexible linker. The EF1-EF2 domain is an EFbeta-scaffold with two bound Ca2+ ions that straddle an N-terminal alpha helix. The GAR domain has a unique alpha/beta sandwich fold that coordinates Zn2+. While the EF1-EF2 domain is not sufficient for MT binding, the GAR domain is and likely enhances EF1-EF2-MT engagement. Residues in a conserved basic patch, distal to the GAR domain's Zn2+-binding site, mediate MT binding.