Defining a core set of actin cytoskeletal proteins critical for actin-based motility of Rickettsia.
Many Rickettsia species are intracellular bacterial pathogens that use actin-based motility for spread during infection. However, while other bacteria assemble actin tails consisting of branched networks, Rickettsia assemble long parallel actin bundles, suggesting the use of a distinct mechanism for exploiting actin. To identify the underlying mechanisms and host factors involved in Rickettsia parkeri actin-based motility, we performed an RNAi screen targeting 115 actin cytoskeletal genes in Drosophila cells. The screen delineated a set of four core proteins-profilin, fimbrin/T-plastin, capping protein, and cofilin--as crucial for determining actin tail length, organizing filament architecture, and enabling motility. In mammalian cells, these proteins were localized throughout R. parkeri tails, consistent with a role in motility. Profilin and fimbrin/T-plastin were critical for the motility of R. parkeri but not Listeria monocytogenes. Our results highlight key distinctions between the evolutionary strategies and molecular mechanisms employed by bacterial pathogens to assemble and organize actin.
Serio
Alisa W
AW
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Jeng
Robert L
RL
Haglund
Cat M
CM
Reed
Shawna C
SC
Welch
Matthew D
MD
D051344:Actin Capping Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051339:Actin Depolymerizing Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D004330:Drosophila; D020868:Gene Silencing; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009038:Motion; D051304:Profilins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012281:Rickettsia / Q000472:pathogenicity*
D051344:Actin Capping Proteins; D051339:Actin Depolymerizing Factors; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D051304:Profilins; D034741:RNA, Small Interfering; C026742:plastin