A Rickettsia WASP-like protein activates the Arp2/3 complex and mediates actin-based motility

Robert L. Jeng, Erin D. Goley, Joseph A. D'Alessio, Oleg Y. Chaga, Tatyana M. Svitkina, Gary G. Borisy, Robert A. Heinzen, Matthew D. Welch

Research output: Contribution to journalArticlepeer-review

107 Scopus citations


Spotted fever group Rickettsia are obligate intracellular pathogens that exploit the host cell actin cytoskeleton to promote motility and cell-to-cell spread. Although other pathogens such as Listeria monocytogenes use an Arp2/3 complex-dependent nucleation mechanism to generate comet tails consisting of Y-branched filament arrays, Rickettsia polymerize tails consisting of unbranched filaments by a previously unknown mechanism. We identified genes in several Rickettsia species encoding proteins (termed RickA) with similarity to the WASP family of Arp2/3-complex activators. Rickettsia rickettsii RickA activated both the nucleation and Y-branching activities of the Arp2/ 3 complex like other WASP-family proteins, and was sufficient to direct the motility of microscopic beads in cell extracts. Actin tails generated by RickA-coated beads consisted of Y-branched filament networks. These data suggest that Rickettsia use an Arp2/3 complex-dependent actin-nucleation mechanism similar to that of other pathogens. We propose that additional Rickettsia or host factors reorganize the Y-branched networks into parallel arrays in a manner similar to a recently proposed model of filopodia formation.

Original languageEnglish (US)
Pages (from-to)761-769
Number of pages9
JournalCellular microbiology
Issue number8
StatePublished - Aug 2004
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology


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