3o4x
Crystal structure of complex between amino and carboxy terminal fragments of mDia1
Structural highlights
FunctionDIAP1_MOUSE Acts in a Rho-dependent manner to recruit PFY1 to the membrane. Required for the assembly of F-actin structures, such as actin cables and stress fibers. Nucleates actin filaments. Binds to the barbed end of the actin filament and slows down actin polymerization and depolymerization. Required for cytokinesis, and transcriptional activation of the serum response factor. DFR proteins couple Rho and Src tyrosine kinase during signaling and the regulation of actin dynamics. Functions as a scaffold protein for MAPRE1 and APC to stabilize microtubules and promote cell migration. Has neurite outgrowth promoting activity. The MEMO1-RHOA-DIAPH1 signaling pathway plays an important role in ERBB2-dependent stabilization of microtubules at the cell cortex. It controls the localization of APC and CLASP2 to the cell membrane, via the regulation of GSK3B activity. In turn, membrane-bound APC allows the localization of the MACF1 to the cell membrane, which is required for microtubule capture and stabilization. Plays a role in the regulation of cell morphology and cytoskeletal organization. Required in the control of cell shape (By similarity).[1] [2] [3] [4] Publication Abstract from PubMedFormin proteins direct the nucleation and assembly of linear actin filaments in a variety of cellular processes using their conserved formin homology 2 (FH2) domain. Diaphanous-related formins (DRFs) are effectors of Rho-family GTPases, and in the absence of Rho activation they are maintained in an inactive state by intramolecular interactions between their regulatory N-terminal region and a C-terminal segment referred to as the DAD domain. Although structures are available for the isolated DAD segment in complex with the interacting region in the N-terminus, it remains unclear how this leads to inhibition of actin assembly by the FH2 domain. Here we describe the crystal structure of the N-terminal regulatory region of formin mDia1 in complex with a C-terminal fragment containing both the FH2 and DAD domains. In the crystal structure and in solution, these fragments form a tetrameric complex composed of two interlocking N+C dimers. Formation of the tetramer is likely a consequence of the particular N-terminal construct employed, as we show that a nearly full-length mDia1 protein is dimeric, as are other autoinhibited N+C complexes containing longer N-terminal fragments. The structure provides the first view of the intact C-terminus of a DRF, revealing the relationship of the DAD to the FH2 domain. Delineation of alternative dimeric N+C interactions within the tetramer provides two general models for autoinhibition in intact formins. In both models, engagement of the DAD by the N-terminus is incompatible with actin filament formation on the FH2, and in one model the actin binding surfaces of the FH2 domain are directly blocked by the N-terminus. Crystal structure of a complex between amino and carboxy terminal fragments of mDia1: insights into autoinhibition of diaphanous-related formins.,Nezami A, Poy F, Toms A, Zheng W, Eck MJ PLoS One. 2010 Sep 30;5(9). pii: e12992. PMID:20927338[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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