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Chlamydia trachomatis responds to heat shock, penicillin induced persistence, and IFN-gamma persistence by altering levels of the extracytoplasmic stress response protease HtrA

Institute of Health and Biomedical Innovation, 60 Musk Ave, Queensland University of Technology, Kelvin Grove, QLD, 4059, Australia.
BMC Microbiology (Impact Factor: 2.98). 02/2008; 8:190. DOI: 10.1186/1471-2180-8-190
Source: PubMed

ABSTRACT Chlamydia trachomatis, an obligate intracellular human pathogen, is the most prevalent bacterial sexually transmitted infection worldwide and a leading cause of preventable blindness. HtrA is a virulence and stress response periplasmic serine protease and molecular chaperone found in many bacteria. Recombinant purified C. trachomatis HtrA has been previously shown to have both activities. This investigation examined the physiological role of Chlamydia trachomatis HtrA.
The Chlamydia trachomatis htrA gene complemented the lethal high temperature phenotype of Escherichia coli htrA- (>42 degrees C). HtrA levels were detected to increase by western blot and immunofluorescence during Chlamydia heat shock experiments. Confocal laser scanning microscopy revealed a likely periplasmic localisation of HtrA. During penicillin induced persistence of Chlamydia trachomatis, HtrA levels (as a ratio of LPS) were initially less than control acute cultures (20 h post infection) but increased to more than acute cultures at 44 h post infection. This was unlike IFN-gamma persistence where lower levels of HtrA were observed, suggesting Chlamydia trachomatis IFN-gamma persistence does not involve a broad stress response.
The heterologous heat shock protection for Escherichia coli, and increased HtrA during cell wall disruption via penicillin and heat shock, indicates an important role for HtrA during high protein stress conditions for Chlamydia trachomatis.

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    • "Activity-based probe binding was conducted on cultures from T25 flasks at different time points, while the competitive binding assays were conducted on cultures from T80 flasks harvested at 22 h PI. Western blots for CtHtrA and MOMP were conducted as previously described (Huston et al., 2008). "
    Dataset: chlamydia
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    • "Activity-based probe binding was conducted on cultures from T25 flasks at different time points, while the competitive binding assays were conducted on cultures from T80 flasks harvested at 22 h PI. Western blots for CtHtrA and MOMP were conducted as previously described (Huston et al., 2008). "
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    • "It has been shown in a wide range of bacterial species that HtrA proteases are essential for virulence and survival under environmental stress. In fact, mutations in the htrA gene have been shown to affect bacterial tolerance to both thermal and environmental stress and to produce a loss of virulence, as shown in Porphyromonas gingivalis, Chlamydia trachomatis, Salmonella typhimurium , Streptococcus pyogenes, Listeria monocytogenes and Burkhoderia cenocepacia (Jones et al. 2001, Biwas & Biwas 2005, Stack et al. 2005, Mo et al. 2006, Flannagan et al. 2007, Huston et al. 2008, Yuan et al. 2008, Lewis et al. 2009). Biochemical analysis of the three HtrA proteins found in Escherichia coli, DegP, DegQ and DegS, has provided insights into their function and regulation (Lipinska et al. 1989, 1990, Kolmar et al. 1996, Krojer et al. 2008). "
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