New view of the surface projections of Chlamydia trachomatis

Abstract

Two kinds of surface specializations of chlamydiae have been described: hemispheric projections and spikelike rods. We undertook the present studies to demonstrate chlamydial ultrastructure in greater detail in conventional thin-sectioned specimens. Chlamydia trachomatis (LGV strain L2/434/Bu), cultured for 40 h in L929 mouse fibroblasts, was fixed in glutaraldehyde-acrolein, p-formaldehyde-glutaraldehyde, or glutaraldehyde-osmium tetroxide mixtures, postfixed in osmium tetroxide, stained in uranyl acetate, dehydrated in ethanols, and embedded in Epon. By the use of fixatives that penetrate and fix rapidly, chlatnydial outer and plasma membranes were clearly revealed. Our results indicate that the hemispheric projections are specializations of the plasma membrane of elementary bodies. The spikelike projections are found in interniediate forms, originate beneath depressions of the plasma membrane, and extend through the periplasmic space and outer membrane to end with pointed tips. Improved preservation of chlamydiae provides a new, informative view of their complex structure. Significant interactions between chlamydiae and host cells might be influenced by the surface structures shown in this study.

Treatment of Chlamydia trachomatis with a small molecule inhibitor of the Yersinia type III secretion system disrupts progression of the chlamydial developmental cycle

“…In all probability this is also true for Chlamydia systems. In support of this notion, injectisome filaments have been visualized protruding through inclusion membranes (Matsumoto, 1981; Nichols et al ., 1985). The membrane‐dependent connection between T3SS and chlamydial development reinforces the possibility that these two complex processes may be linked.…”

Alteration of chlamydia trachomatis biologic behavior in synovial membranes suppression of surface antigen production in reactive arthritis and reiter's syndrome

“…Positive IGS results for at least 2 chlamydial surface antigens, in at least 2 consecutive cuts of ultrathin sections, were required for organism identification. Ultrastructural characterization of chlamydial particles, as described in the literature (29)(30)(31)(32), was essential to recognition of these particles, in which IGS findings for the surface antigens were weak or negative.…”

Architecture and host interface of environmental chlamydiae revealed by electron cryotomography

“…Internalization, inclusion development and hostorganelle recruitment are all mediated by the secretion of effector proteins into the inclusion membrane and/or host cytoplasm by the type III secretion (T3S) system (Peters et al, 2007). While the genes that encode this needle-like secretion system are present in all chlamydial genomes (Collingro et al, 2011), T3S structures have not been seen in environmental chlamydiae, and few structural details are known about the T3S systems of pathogenic chlamydiae (Matsumoto, 1979;Nichols et al, 1985;Dumoux et al, 2012).…”