title: Endocytic internalization in budding yeast requires coordinated actin nucleation and myosin motor activity.
abstract: Actin polymerization essential for endocytic internalization in budding yeast is controlled by four nucleation promoting factors (NPFs) that each exhibits a unique dynamic behavior at endocytic sites. How each NPF functions and is regulated to restrict actin assembly to late stages of endocytic internalization is not known. Quantitative analysis of NPF biochemical activities, and genetic analysis of recruitment and regulatory mechanisms, defined a linear pathway in which protein composition changes at endocytic sites control actin assembly and function. We show that yeast WASP initiates actin assembly at endocytic sites and that this assembly and the recruitment of a yeast WIP-like protein by WASP recruit a type I myosin with both NPF and motor activities. Importantly, type I myosin motor and NPF activities are separable, and both contribute to endocytic coat inward movement, which likely represents membrane invagination. These results reveal a mechanism in which actin nucleation and myosin motor activity cooperate to promote endocytic internalization.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
authors.forename: Yidi
authors.initials: Y
authors.lastname: Sun
authors.forename: Adam C
authors.initials: AC
authors.lastname: Martin
authors.forename: David G
authors.initials: DG
authors.lastname: Drubin
mesh_terms: D000199:Actins / Q000737:chemistry / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*; D005800:Genes, Fungal; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000502:physiology; D009068:Movement; D009154:Mutation; D018995:Myosin Heavy Chains / Q000235:genetics / Q000502:physiology; D024461:Myosin Type I / Q000235:genetics / Q000502:physiology; D009218:Myosins / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051316:Wiskott-Aldrich Syndrome Protein / Q000502:physiology
chemical_list: D000199:Actins; C480361:LAS17 protein, S cerevisiae; C491722:MYO3 protein, S cerevisiae; C100412:MYO5 protein, S cerevisiae; D020409:Molecular Motor Proteins; D029701:Saccharomyces cerevisiae Proteins; D051316:Wiskott-Aldrich Syndrome Protein; D024461:Myosin Type I; D018995:Myosin Heavy Chains; D009218:Myosins