title: Common formin-regulating sequences in Smy1 and Bud14 are required for the control of actin cable assembly in vivo.
abstract: Formins comprise a large family of proteins with diverse roles in remodeling the actin cytoskeleton. However, the spatiotemporal mechanisms used by cells to control formin activities are only beginning to be understood. Here we dissected Smy1, which has dual roles in regulating formins and myosin. Using mutagenesis, we identified specific sequences in Smy1 critical for its in vitro inhibitory effects on the FH2 domain of the formin Bnr1. By integrating smy1 alleles targeting those sequences, we genetically uncoupled Smy1's functions in regulating formins and myosin. Quantitative imaging analysis further demonstrated that the ability of Smy1 to directly control Bnr1 activity is crucial in vivo for proper actin cable length, shape, and velocity and, in turn, efficient secretory vesicle transport. A Smy1-like sequence motif was also identified in a different Bnr1 regulator, Bud14, and found to be essential for Bud14 functions in regulating actin cable architecture and function in vivo. Together these observations reveal unanticipated mechanistic ties between two distinct formin regulators. Further, they emphasize the importance of tightly controlling formin activities in vivo to generate specialized geometries and dynamics of actin structures tailored to their physiological roles.
authors.affiliation: Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.
authors.forename: Julian A
authors.initials: JA
authors.lastname: Eskin
authors.affiliation: Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.
authors.forename: Aneliya
authors.initials: A
authors.lastname: Rankova
authors.affiliation: Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.
authors.forename: Adam B
authors.initials: AB
authors.lastname: Johnston
authors.affiliation: Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.
authors.forename: Salvatore L
authors.initials: SL
authors.lastname: Alioto
authors.affiliation: Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454 goode@brandeis.edu.
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Goode
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism; D009218:Myosins / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C106463:BNR1 protein, S cerevisiae; C474555:Bud14 protein, S cerevisiae; D003598:Cytoskeletal Proteins; C077512:MYO2 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C087665:kinesin-like protein 1; D049452:Green Fluorescent Proteins; D024701:Myosin Type V; C064320:SEC4 protein, S cerevisiae; D018995:Myosin Heavy Chains; D009218:Myosins; D020691:rab GTP-Binding Proteins