The diaphanous inhibitory domain/diaphanous autoregulatory domain interaction is able to mediate heterodimerization between mDia1 and mDia2.
Formins are multidomain proteins that regulate numerous cytoskeleton-dependent cellular processes. These effects are mediated by the presence of two regions of homology, formin homology 1 and FH2. The diaphanous-related formins (DRFs) are distinguished by the presence of interacting N- and C-terminal regulatory domains. The GTPase binding domain and diaphanous inhibitory domain (DID) are found in the N terminus and bind to the diaphanous autoregulatory domain (DAD) found in the C terminus. Adjacent to the DID is an N-terminal dimerization motif (DD) and coiled-coil region (CC). The N terminus of Dia1 is also proposed to contain a Rho-independent membrane-targeting motif. We undertook an extensive structure/function analysis of the mDia1 N terminus to further our understanding of its role in vivo. We show here that both DID and DD are required for efficient autoinhibition in the context of full-length mDia1 and that the DD of mDia1 and mDia2, like formin homology 2, mediates homo- but not heterodimerization with other DRF family members. In contrast, our results suggest that the DID/DAD interaction mediates heterodimerization of full-length mDia1 and mDia2 and that the auto-inhibited conformation of DRFs is oligomeric. In addition, we also show that the DD/CC region is required for the Rho-independent membrane targeting of the isolated N terminus.
Copeland
Sarah J
SJ
Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
Green
Brenda J
BJ
Burchat
Sarah
S
Papalia
Giuseppe A
GA
Banner
David
D
Copeland
John W
JW
D000199:Actins / Q000737:chemistry; D020816:Amino Acid Motifs; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D000080865:Formins; D005786:Gene Expression Regulation; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D008869:Microtubule-Associated Proteins; D008954:Models, Biological; D009252:NADPH Dehydrogenase / Q000737:chemistry*; D041681:NIH 3T3 Cells; D011485:Protein Binding; D017434:Protein Structure, Tertiary
D000199:Actins; D002352:Carrier Proteins; C491464:Diap1 protein, mouse; D000080865:Formins; D008869:Microtubule-Associated Proteins; C508552:Dia2 protein, mouse; D009252:NADPH Dehydrogenase