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: We tested for such a role in chlamydial extrusion by counting the extrusions released between 48 h and 66 h p.i. (11, 12). Using either siRNA directed against SEPT9 alone or the combinations of siRNA specific for SEPT2, -7, and -9, we found a 2- to 3-fold reduction in the numbers of extrusions when the septins were knocked down (Fig. 6A). Determination of infectious bacteria released by extrusion showed an about 4-fold reduction when SEPT9 was knocked down (Fig. 6B). Septins thus appear to be required for the normal organization of chlamydial exit by extrusion.
Affiliation: Institute for Medical Microbiology and Hygiene, University Medical Center Freiburg, Freiburg, Germany.