Arf6 coordinates actin assembly through the WAVE complex, a mechanism usurped by Salmonella to invade host cells

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-10, Vol.110 (42), p.16880-16885
• Main Authors: Humphreys, Daniel, Davidson, Anthony C., Hume, Peter J., Makin, Laura E., Koronakis, Vassilis
• Format: Article
• Language: English
• Subjects: actin; Actins; Actins - genetics; Actins - metabolism; ADP-Ribosylation Factor 1 - genetics; ADP-Ribosylation Factor 1 - metabolism; ADP-Ribosylation Factor 6; ADP-Ribosylation Factors - genetics; ADP-Ribosylation Factors - metabolism; Bacteria; Biological Sciences; Cell membranes; Cells; Cytoskeleton; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; guanosinetriphosphatase; HeLa Cells; Humans; Immunoblotting; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membranes; microfilaments; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; P branes; pathogens; physiological transport; plasma membrane; Polymerization; Salmonella; Salmonella - metabolism; Salmonella - pathogenicity; Salmonella Infections - genetics; Salmonella Infections - metabolism; Signal Transduction; Small interfering RNA; Sulfotransferases - genetics; Sulfotransferases - metabolism; Transfection
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1311680110

ADP ribosylation factor (Arf) 6 anchors to the plasma membrane, where it coordinates membrane trafficking and cytoskeleton remodelling, but how it assembles actin filaments is unknown. By reconstituting membrane-associated actin assembly mediated by the WASP family veroprolin homolog (WAVE) regulatory complex (WRC), we recapitulated an Arf6-driven actin polymerization pathway. We show that Arf6 is divergent from other Arf members, as it was incapable of directly recruiting WRC. We demonstrate that Arf6 triggers actin assembly at the membrane indirectly by recruiting the Arf g uanine nucleotide exchange factor (GEF) ARNO that activates Arf1 to enable WRC-dependent actin assembly. The pathogen Salmonella usurped Arf6 for host cell invasion by recruiting its canonical GEFs EFA6 and BRAG2. Arf6 and its GEFs facilitated membrane ruffling and pathogen invasion via ARNO, and triggered actin assembly by generating an Arf1–WRC signaling hub at the membrane in vitro and in cells. This study reconstitutes Arf6-dependent actin assembly to reveal a mechanism by which related Arf GTPases orchestrate distinct steps in the WRC cytoskeleton remodelling pathway.