title: Requirement for the Rac GTPase in Chlamydia trachomatis invasion of non-phagocytic cells.
abstract: Chlamydiae are gram-negative obligate intracellular pathogens to which access to an intracellular environment is paramount to their survival and replication. To this end, chlamydiae have evolved extremely efficient means of invading nonphagocytic cells. To elucidate the host cell machinery utilized by Chlamydia trachomatis in invasion, we examined the roles of the Rho GTPase family members in the internalization of chlamydial elementary bodies. Upon binding of elementary bodies on the cell surface, actin is rapidly recruited to the sites of internalization. Members of the Rho GTPase family are frequently involved in localized recruitment of actin. Clostridial Toxin B, which is a known enzymatic inhibitor of Rac, Cdc42 and Rho GTPases, significantly reduced chlamydial invasion of HeLa cells. Expression of dominant negative constructs in HeLa cells revealed that chlamydial uptake was dependent on Rac, but not on Cdc42 or RhoA. Rac but not Cdc42 was found to be activated by chlamydial attachment. The effect of dominant negative Rac expression on chlamydial uptake is manifested through the inhibition of actin recruitment to the sites of chlamydial entry. Studies utilizing Green Fluorescent Protein fusion constructs of Rac, Cdc42 and RhoA, showed Rac to be the sole member of the Rho GTPase family recruited to the site of chlamydial entry.
authors.affiliation: Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
authors.forename: Rey A
authors.initials: RA
authors.lastname: Carabeo
authors.forename: Scott S
authors.initials: SS
authors.lastname: Grieshaber
authors.forename: Aaron
authors.initials: A
authors.lastname: Hasenkrug
authors.forename: Cheryl
authors.initials: C
authors.lastname: Dooley
authors.forename: Ted
authors.initials: T
authors.lastname: Hackstadt
mesh_terms: D000199:Actins / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D002692:Chlamydia trachomatis / Q000201:enzymology* / Q000502:physiology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D010587:Phagocytosis / Q000187:drug effects*; D010957:Plasmids / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D001427:Bacterial Toxins; D004791:Enzyme Inhibitors; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D020744:rac GTP-Binding Proteins