title: The myosin passenger protein Smy1 controls actin cable structure and dynamics by acting as a formin damper.
abstract: Formins are a conserved family of proteins with robust effects in promoting actin nucleation and elongation. However, the mechanisms restraining formin activities in cells to generate actin networks with particular dynamics and architectures are not well understood. In S. cerevisiae, formins assemble actin cables, which serve as tracks for myosin-dependent intracellular transport. Here, we show that the kinesin-like myosin passenger-protein Smy1 interacts with the FH2 domain of the formin Bnr1 to decrease rates of actin filament elongation, which is distinct from the formin displacement activity of Bud14. In vivo analysis of smy1Δ mutants demonstrates that this "damper" mechanism is critical for maintaining proper actin cable architecture, dynamics, and function. We directly observe Smy1-3GFP being transported by myosin V and transiently pausing at the neck in a manner dependent on Bnr1. These observations suggest that Smy1 is part of a negative feedback mechanism that detects cable length and prevents overgrowth.
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Chesarone-Cataldo
authors.forename: Christophe
authors.initials: C
authors.lastname: Guérin
authors.forename: Jerry H
authors.initials: JH
authors.lastname: Yu
authors.forename: Roland
authors.initials: R
authors.lastname: Wedlich-Soldner
authors.forename: Laurent
authors.initials: L
authors.lastname: Blanchoin
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Goode
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D024701:Myosin Type V / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000199:Actins; C106463:BNR1 protein, S cerevisiae; C474555:Bud14 protein, S cerevisiae; D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D024701:Myosin Type V