title: Arp2/3 complex ATP hydrolysis promotes lamellipodial actin network disassembly but is dispensable for assembly.
abstract: We examined the role of ATP hydrolysis by the Arp2/3 complex in building the leading edge of a cell by studying the effects of hydrolysis defects on the behavior of the complex in the lamellipodial actin network of Drosophila S2 cells and in a reconstituted, in vitro, actin-based motility system. In S2 cells, nonhydrolyzing Arp2 and Arp3 subunits expanded and delayed disassembly of lamellipodial actin networks and the effect of mutant subunits was additive. Arp2 and Arp3 ATP hydrolysis mutants remained in lamellipodial networks longer and traveled greater distances from the plasma membrane, even in networks still containing wild-type Arp2/3 complex. In vitro, wild-type and ATP hydrolysis mutant Arp2/3 complexes each nucleated actin and built similar dendritic networks. However, networks constructed with Arp2/3 hydrolysis-defective mutants were more resistant to disassembly by cofilin. Our results indicate that ATP hydrolysis on both Arp2 and Arp3 contributes to dissociation of the complex from the actin network but is not strictly necessary for lamellipodial network disassembly.
authors: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Elena
authors: E
authors: Ingerman
authors: Jennifer Ying
authors: JY
authors: Hsiao
authors: R Dyche
authors: RD
authors: Mullins
mesh_terms: D008841:Actin Cytoskeleton / Q000201:enzymology*; D051377:Actin-Related Protein 2 / Q000235:genetics / Q000378:metabolism; D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D051378:Actin-Related Protein 3 / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D051338:Cofilin 1 / Q000378:metabolism; D004330:Drosophila; D005838:Genotype; D006868:Hydrolysis; D008856:Microscopy, Fluorescence; D009154:Mutation; D010641:Phenotype; D051304:Profilins / Q000378:metabolism; D011554:Pseudopodia / Q000201:enzymology*; D034622:RNA Interference; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: C495926:ACTR2 protein, human; C495928:ACTR3 protein, human; C477632:ARP2 protein, S cerevisiae; C102245:ARP3 protein, S cerevisiae; D051377:Actin-Related Protein 2; D051376:Actin-Related Protein 2-3 Complex; D051378:Actin-Related Protein 3; C495810:CFL1 protein, human; D051338:Cofilin 1; C495738:PFN1 protein, human; D051304:Profilins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate