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Structure. 2008 Sep 10;16(9):1313-23. doi: 10.1016/j.str.2008.06.008.

The human formin FHOD1 contains a bipartite structure of FH3 and GTPase-binding domains required for activation.

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1
Abteilung Physikalische Biochemie, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.

Abstract

Formins induce the nucleation and polymerization of unbranched actin filaments. They share three homology domains required for profilin binding, actin polymerization, and regulation. Diaphanous-related formins (DRFs) are activated by GTPases of the Rho/Rac family, whose interaction with the N-terminal formin domain is thought to displace a C-terminal Diaphanous-autoregulatory domain (DAD). We have determined the structure of the N-terminal domains of FHOD1 consisting of a GTPase-binding domain (GBD) and the DAD-recognition domain FH3. In contrast to the formin mDia1, the FHOD1-GBD reveals a ubiquitin superfold as found similarly in c-Raf1 or PI3 kinase. This GBD is recruited by Rac and Ras GTPases in cells and plays an essential role for FHOD1-mediated actin remodeling. The FHOD1-FH3 domain is composed of five armadillo repeats, similarly to other formins. Mutation of one residue in the predicted DAD-interaction surface efficiently activates FHOD1 in cells. These results demonstrate that DRFs have evolved different molecular solutions to govern their autoregulation and GTPase specificity.

PMID:
18786395
DOI:
10.1016/j.str.2008.06.008
[Indexed for MEDLINE]
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