title: Interactions of WASp, myosin-I, and verprolin with Arp2/3 complex during actin patch assembly in fission yeast.
abstract: Yeast actin patches are dynamic structures that form at the sites of cell growth and are thought to play a role in endocytosis. We used biochemical analysis and live cell imaging to investigate actin patch assembly in fission yeast Schizosaccharomyces pombe. Patch assembly proceeds via two parallel pathways: one dependent on WASp Wsp1p and verprolin Vrp1p converges with another dependent on class 1 myosin Myo1p to activate the actin-related protein 2/3 (Arp2/3) complex. Wsp1p activates Arp2/3 complex via a conventional mechanism, resulting in branched filaments. Myo1p is a weaker Arp2/3 complex activator that makes unstable branches and is enhanced by verprolin. During patch assembly in vivo, Wsp1p and Vrp1p arrive first independent of Myo1p. Arp2/3 complex associates with nascent activator patches over 6-9 s while remaining stationary. After reaching a maximum concentration, Arp2/3 complex patches move centripetally as activator proteins dissociate. Genetic dependencies of patch formation suggest that patch formation involves cross talk between Myo1p and Wsp1p/Vrp1p pathways.
authors.affiliation: Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Sirotkin
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Beltzner
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Marchand
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Pollard
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002470:Cell Survival; D008840:Microfilament Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D024461:Myosin Type I / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017384:Sequence Deletion; D013997:Time Factors
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; C523603:Vrp1 protein, S pombe; C417034:Wsp1 protein, S pombe; D024461:Myosin Type I