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: This finding prompted us to investigate the structure of septins during chlamydial infection. Immunostaining for SEPT2 showed that SEPT2-containing fibers encased the chlamydial inclusion, starting from about 16 h postinfection (p.i.) (Fig. 1). In most cells, fibers that ran across the inclusion were observed, often visible as a ring around the inclusion in epifluorescence microscopy. Confocal imaging and orthogonal views of the reconstructed image show fibers containing SEPT2 (see Fig. S2A and B in the supplemental material) and SEPT9 (see Fig. S2C) at the bottom of the inclusion, around it, and at its top. The structures are suggestive of larger-order structures since they are well known to be formed by septins.
Affiliation: Institute for Medical Microbiology and Hygiene, University Medical Center Freiburg, Freiburg, Germany.