Lipid metabolism in Chlamydia trachomatis-infected cells: Directed trafficking of Golgi-derived sphingolipids to the chlamydial inclusion

Host-Parasite Interactions Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 06/1995; 92(11):4877-81. DOI: 10.1073/pnas.92.11.4877
Source: PubMed

ABSTRACT Chlamydia trachomatis undergoes its entire life cycle within an uncharacterized intracellular vesicle that does not fuse with lysosomes. We used a fluorescent Golgi-specific probe, (N-[7-(4-nitrobenzo-2-oxa-1,3-diazole)]) aminocaproylsphingosine (C6-NBD-Cer), in conjunction with conventional fluorescence or confocal microscopy to identify interactions between the Golgi apparatus and the chlamydial inclusion. We observed not only a close physical association between the Golgi apparatus and the chlamydial inclusion but the eventual presence of a metabolite of this fluorescent probe associated with the chlamydiae themselves. Sphingomyelin, endogenously synthesized from C6-NBD-Cer, was specifically transported to the inclusion and incorporated into the cell wall of the intracellular chlamydiae. Incorporation of the fluorescent sphingolipid by chlamydiae was inhibited by brefeldin A. Chlamydiae therefore occupy a vesicle distal to the Golgi apparatus that receives anterograde vesicular traffic from the Golgi normally bound for the plasma membrane. Collectively, the data suggest that the chlamydial inclusion may represent a unique compartment within the trans-Golgi network.

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Available from: Marci A Scidmore, May 21, 2014
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    • "seven in C. trachomatis). Due to its high immunogenicity in guinea pigs, IncA of C. caviae was the first Inc protein to be discovered (Rockey, Heinzen and Hackstadt 1995). While the members of this protein family display little general sequence similarity, they share a characteristic bilobed hydrophobic domain of 60–80 amino acid residues. "
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    ABSTRACT: Chlamydia (C.) psittaci is an economically relevant pathogen in poultry and pet birds, where it causes psittacosis/ornithosis, and also a human pathogen causing atypical pneumonia after zoonotic transmission. Despite its well-documented prevalence, the agent has received less attention by researchers than other Chlamydia spp. in the last decades. In the present paper, we review recently published data on C. psittaci infection and attempt to single out characteristic features distinguishing it from related chlamydial agents. It is remarkable that C. psittaci is particularly efficient in disseminating in the host organism causing systemic disease, which occasionally can take a fulminant course. At the cellular level, the pathogen's broad host cell spectrum (from epithelial cells to macrophages), its rapid entry and fast replication, proficient use of intracellular transport routes to mitochondria and the Golgi apparatus, the pronounced physical association of chlamydial inclusions with energy-providing cell compartments, as well as the subversive regulation of host cell survival during productive and persistent states facilitate the characteristic efficient growth and successful host-to-host spread of C. psittaci. At the molecular level, the pathogen was shown to upregulate essential chlamydial genes when facing the host immune response. We hypothesize that this capacity, in concert with expression of specific effectors of the type III secretion system and efficient suppression of selected host defense signals, contributes to successful establishment of the infection in the host. Concerning the immunology of host-pathogen interactions, C. psittaci has been shown to distinguish itself by coping more efficiently than other chlamydiae with pro-inflammatory mediators during early host response, which can, to some extent, explain the effective evasion and adaptation strategies of this bacterium. We conclude that thorough analysis of the large number of whole-genome sequences already available will be essential to identify genetic markers of the species-specific features and trigger more in-depth studies in cellular and animal models to address such vital topics as treatment and vaccination. © FEMS 2014. All rights reserved. For permissions, please e-mail:
    Pathogens and Disease 12/2014; 73(1). DOI:10.1093/femspd/ftu007 · 2.40 Impact Factor
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    • "However, growth in the inclusion also necessitates the acquisition of nutrients across the inclusion membrane including host-derived membrane lipids (sphingomyelin and cholesterol) as well as phospholipids for the growing inclusion membrane and the bacteria themselves [4]–[7]. In 1995, Ted Hackstadt and colleagues showed that exogenously added ceramide is converted to sphingomyelin within the host cell and taken up into the bacterial cell wall [8]. Since then, many studies have investigated aspects of lipid transport to the chlamydial inclusion (for review see [9]). "
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    ABSTRACT: Chlamydia grows inside a cytosolic vacuole (the inclusion) that is supplied with nutrients by the host through vesicular and non-vesicular transport. It is unclear in many respects how Chlamydia organizes this transport. One model posits that the Chlamydia-induced fragmentation of the Golgi-apparatus is required for normal transport processes to the inclusion and for chlamydial development, and the chlamydial protease CPAF has been controversially implicated in Golgi-fragmentation. We here use a model of penicillin-induced persistence of infection with Chlamydia trachomatis to test this link. Under penicillin-treatment the inclusion grew in size for the first 24 h but after that growth was severely reduced. Penicillin did not reduce the number of infected cells with fragmented Golgi-apparatus, and normal Golgi-fragmentation was found in a CPAF-deficient mutant. Surprisingly, sphingomyelin transport into the inclusion and into the bacteria, as measured by fluorescence accumulation upon addition of labelled ceramide, was not reduced during penicillin-treatment. Thus, both Golgi-fragmentation and transport of sphingomyelin to C. trachomatis still occurred in this model of persistence. The portion of cells in which CPAF was detected in the cytosol, either by immunofluorescence or by immune-electron microscopy, was drastically reduced in cells cultured in the presence of penicillin. These data argue against an essential role of cytosolic CPAF for Golgi-fragmentation or for sphingomyelin transport in chlamydial infection.
    PLoS ONE 07/2014; 9(7):e103220. DOI:10.1371/journal.pone.0103220 · 3.23 Impact Factor
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    • "First, plasmalogens synthesized in the host cell cytoplasm may be imported first into the inclusion and subsequently into Chlamydia. Such a two-step mechanism operates for at least part of sphingomyelin and cholesterol transport, with the inclusion intercepting both vesicular [4], [7] and non-vesicular [31], [32] trafficking pathways. They could then be modified by Chlamydia, replacing the fatty acid at the sn-2 position with a 15- or 17-carbon bacterial fatty acid. "
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    ABSTRACT: Chlamydia trachomatis is an obligate intracellular pathogen responsible for loss of eyesight through trachoma and for millions of cases annually of sexually transmitted diseases. The bacteria develop within a membrane-bounded inclusion. They lack enzymes for several biosynthetic pathways, including those to make some phospholipids, and exploit their host to compensate. Three-dimensional fluorescence microscopy demonstrates that small organelles of the host, peroxisomes, are translocated into the Chlamydia inclusion and are found adjacent to the bacteria. In cells deficient for peroxisome biogenesis the bacteria are able to multiply and give rise to infectious progeny, demonstrating that peroxisomes are not essential for bacterial development in vitro. Mass spectrometry-based lipidomics reveal the presence in C. trachomatis of plasmalogens, ether phospholipids whose synthesis begins in peroxisomes and have never been described in aerobic bacteria before. Some of the bacterial plasmalogens are novel structures containing bacteria-specific odd-chain fatty acids; they are not made in uninfected cells nor in peroxisome-deficient cells. Their biosynthesis is thus accomplished by the metabolic collaboration of peroxisomes and bacteria.
    PLoS ONE 01/2014; 9(1):e86196. DOI:10.1371/journal.pone.0086196 · 3.23 Impact Factor
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