Septins arrange F-actin-containing fibers on the Chlamydia trachomatis inclusion and are required for normal release of the inclusion by extrusion.
Bottom Line: RNAi against SEPT9 or against the combination of SEPT2/7/9 substantially reduced the number of extrusions from a culture of infected HeLa cells.Septins have previously been found to be involved in the interaction of the cell with bacteria in the cytosol.Our observation that they also organize a reaction to bacteria living in vacuoles suggests that they have a function in the recognition of foreign compartments by a parasitized human cell.
Affiliation: Institute for Medical Microbiology and Hygiene, University Medical Center Freiburg, Freiburg, Germany.Show MeSH
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Mentions: The colocalization of septins with actin and the reported reciprocal interactions of septins and actin suggested the possibility of a functional interdependence of these two components. We therefore targeted septins by RNAi and stained for F actin during infection. Indeed, knockdown of either SEPT9 (Fig. 5A; see also Fig. S6A in the supplemental material) or SEPT2 (Fig. 5B) caused the reduction or loss of identifiable actin fibers on the inclusion. Conversely, when actin polymerization was inhibited by treatment with cytochalasin D, SEPT2 and -9 structures on the inclusion were also disrupted (Fig. 5C).
Affiliation: Institute for Medical Microbiology and Hygiene, University Medical Center Freiburg, Freiburg, Germany.