The basic region of the diaphanous-autoregulatory domain (DAD) is required for autoregulatory interactions with the diaphanous-related formin inhibitory domain.
Mammalian diaphanous-related (mDia) formins act as Rho GTPase effectors during cytoskeletal remodeling. Rho binding to mDia amino-terminal GTPase-binding domains (GBDs) causes the adjacent Dia-inhibitory domain (DID) to release the carboxyl-terminal Dia-autoregulatory (DAD) domain that flanks the formin homology-2 (FH2) domain. The release of DAD allows the FH2 domain to then nucleate and elongate nonbranched actin filaments. DAD, initially discovered as a region of homology shared between a phylogenetically divergent set of formin proteins, is comprised of a core motif, MDXLLXL, and an adjacent region is comprised of numerous basic residues, typically RRKR in the mDia family. Here, we show that these specific amino acids within the basic region of DAD contribute to the binding of DID and therefore the maintenance of the mDia autoregulatory mechanism. In addition, expression of full-length versions of mDia2 containing amino acid substitutions in either the DAD core or basic regions causes profound changes in the F-actin architecture, including the formation of filopodia-like structures that rapidly elongate from the cell edge. These studies further refine our understanding of the molecular contribution of DAD to mDia control and the role of mDia2 in the assembly of membrane protrusions.
Wallar
Bradley J
BJ
Chemistry Department and Cell and Molecular Biology Program, Grand Valley State University, Allendale, Michigan 49401-9403, USA.
Stropich
Brittany N
BN
Schoenherr
Jessica A
JA
Holman
Holly A
HA
Kitchen
Susan M
SM
Alberts
Arthur S
AS
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D000080865:Formins; D006706:Homeostasis; D051379:Mice; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009252:NADPH Dehydrogenase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D041681:NIH 3T3 Cells; 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