Role of actin polymerization and actin cables in actin-patch movement in Schizosaccharomyces pombe.
Factors that are involved in actin polymerization, such as the Arp2/3 complex, have been found to be packaged into discrete, motile, actin-rich foci. Here we investigate the mechanism of actin-patch motility in S. pombe using a fusion of green fluorescent protein (GFP) to a coronin homologue, Crn1p. Actin patches are associated with cables and move with rates of 0.32 microm s(-1) primarily in an undirected manner at cell tips and also in a directed manner along actin cables, often away from cell tips. Patches move more slowly or stop when actin polymerization is attenuated by Latrunculin A or in arp3 and cdc3 (profilin) mutants. In a cdc8 (tropomyosin) mutant, actin cables are absent, and patches move with similar speed but in a non-directed manner. Patches are sites of Arp3-dependent F-actin polymerization in vitro. Rapid F-actin turnover rates in vivo indicate that patches and cables are maintained continuously by actin polymerization. Our studies give rise to a model in which actin patches are centres for actin polymerization that drive their own movement on actin cables using Arp2/3-based actin polymerization.
Department of Microbiology, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, New York 10032, USA.
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RJ
Pelham
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F
Chang
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D003285:Contractile Proteins; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D018715:Microscopy, Video; D011108:Polymers / Q000378:metabolism; D051304:Profilins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins; D013696:Temperature; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D013997:Time Factors; D014335:Tropomyosin / Q000378:metabolism
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; C410737:Cdc8 protein, S pombe; D018797:Cell Cycle Proteins; D003285:Contractile Proteins; D003598:Cytoskeletal Proteins; D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D008840:Microfilament Proteins; D011108:Polymers; D051304:Profilins; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D013844:Thiazoles; D053778:Thiazolidines; D014335:Tropomyosin; C490133:cdc3 protein, S pombe; C072061:coronin proteins; D049452:Green Fluorescent Proteins; C037067:latrunculin A