Identification and characterization of secreted effector proteins of Chlamydophila pneumoniae TW183

Herrmann, Michael; Schuhmacher, Alexander; Mühldorfer, Inge; Melchers, Klaus; Prothmann, Christian; Dammeier, Sascha

doi:10.1016/j.resmic.2005.12.005

Cited by 29 publications

(32 citation statements)

References 70 publications

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“…pneumoniae and present studies in Cp. psittaci showed inclusion membrane and inclusion body associated SctW [9,16,23]. This supports the hypothesis of SctW being a soluble protein blocking the transmembrane channel [9,33].…”

Section: T3s Gene Expression Analysissupporting

confidence: 84%

“…pneumoniae are supposed to actively modify inclusion membranes with a set of T3S effector proteins, known as inclusion membrane proteins or Incs [10,30,36]. Additional chlamydial T3S effector proteins like the translocated actin recruiting phosphoprotein (Tarp) involved in chlamydial entry [4] and the class I accessible protein-1 (Cap1), an inclusion membrane associated protein recognized by protective CD8 + T cells [2,13] as Pkn5, a putative serine-threonine kinase [11,16,17].…”

Section: Introductionmentioning

confidence: 99%

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Identification and characterization of a type III secretion system inChlamydophila psittaci

Beeckman

Geens²,

Timmermans³

et al. 2008

Vet. Res.

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-Chlamydiaceae are obligate intracellular Gram-negative bacteria replicating in vacuoles inside eukaryotic cells. It has been proven that most of them possess a type III secretion system (T3SS) allowing them to transfer effector molecules in the host cell. We examined the existence of a T3SS in Chlamydophila psittaci by studying the expression of three essential structural proteins SctW, SctC, and SctN, and one putative effector protein IncA. Immunofluorescence assays showed SctW and IncA to be associated with the bacteria and the inclusion membrane, while SctC and SctN were only localized to the bacteria itself. Immuno electron microscopy could confirm these results for SctW, IncA, and SctC. Unfortunately, SctN was not investigated with this technique. Additionally, we sequenced 14 full-length T3S genes (scc1, sctW, sctJ, sctL, sctR, sctS, scc2, copD1, sctN, sctQ, sctC, incA, ca037, and cadd) and examined the transcription of 26 Cp. psittaci T3S genes namely cluster 1 (scc1,

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Section: T3s Gene Expression Analysissupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Identification and characterization of a type III secretion system inChlamydophila psittaci

Beeckman

Geens²,

Timmermans³

et al. 2008

Vet. Res.

View full text Add to dashboard Cite

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“…Additionally, the T3S chaperones are generally not secreted but rather aid in the secretion of their effectors. Previous studies of CT670 and its C. pneumoniae homolog, CPn0706, indicated that these proteins are not secreted (24,47). However, CT671 was shown to be secreted by a heterologous T3S system, and its homolog was detected in the host cytosol of infected cells (53).…”

Section: Discussionmentioning

confidence: 95%

“…However, based on similarities in size, charge distribution, and predicted secondary structure, CT670 is thought to be the Chlamydia trachomatis equivalent of YscO, a mobile core component of the T3S system in Yersinia (40). Previous studies of CPn0706, the Chlamydophila pneumoniae homolog of CT670, indicated that this protein was localized in the inclusion in infected cells, but it was not detected in the inclusion membrane or host cytosol, suggesting that it is not a secreted protein (24). Moreover, CT670 is not expected to be a type III secreted effector on the basis of the results obtained by a computational approach that was used to predict type III secreted effectors by comparison of sequences to sequences of known effectors (47).…”

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confidence: 95%

Structure and Protein-Protein Interaction Studies on Chlamydia trachomatis Protein CT670 (YscO Homolog)

et al. 2010

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Comparative genomic studies have identified many proteins that are found only in various Chlamydiae species and exhibit no significant sequence similarity to any protein in organisms that do not belong to this group. The CT670 protein of Chlamydia trachomatis is one of the proteins whose genes are in one of the type III secretion gene clusters but whose cellular functions are not known. CT670 shares several characteristics with the YscO protein of Yersinia pestis, including the neighboring genes, size, charge, and secondary structure, but the structures and/or functions of these proteins remain to be determined. Although a BLAST search with CT670 did not identify YscO as a related protein, our analysis indicated that these two proteins exhibit significant sequence similarity. In this paper, we report that the CT670 crystal, solved at a resolution of 2 Å, consists of a single coiled coil containing just two long helices. Gel filtration and analytical ultracentrifugation studies showed that in solution CT670 exists in both monomeric and dimeric forms and that the monomer predominates at lower protein concentrations. We examined the interaction of CT670 with many type III secretion system-related proteins (viz., CT091, CT665, CT666, CT667, CT668, CT669, CT671, CT672, and CT673) by performing bacterial two-hybrid assays. In these experiments, CT670 was found to interact only with the CT671 protein (YscP homolog), whose gene is immediately downstream of ct670. A specific interaction between CT670 and CT671 was also observed when affinity chromatography pull-down experiments were performed. These results suggest that CT670 and CT671 are putative homologs of the YcoO and YscP proteins, respectively, and that they likely form a chaperone-effector pair.Chlamydiae are obligate intracellular bacteria that infect a variety of eukaryotes, including humans, animals, insects, and free-living amoebae (8, 31, 51). They are highly pathogenic and cause genital tract, ocular, and respiratory infections in humans (9, 55). A key characteristic of Chlamydiae is their biphasic developmental cycle, in which the bacteria alternate between two morphologies: the elementary body and the reticulate body (1, 31). The Chlamydiae species, like many other Gram-negative pathogenic bacteria, contain a type III secretion (T3S) system, which plays a major role in their pathogenicity (4, 7, 44). This key system aids pathogenicity by exporting bacterial proteins, termed effectors, into the host cell via a syringe-like nanomachine called an injectisome (4, 7). Once secreted into the host cell, these effectors may manipulate host cell functions to the advantage of the pathogen (44, 54).Because of the unique chlamydial developmental cycle currently there are no tractable methods for genetic manipulation of these organisms (25,49). Detailed bioinformatic investigations have identified approximately 200 proteins unique to various taxonomic levels of the Chlamydiae phylum (19, 21). Included in this pool of proteins are proteins whose genes occur in chlamydi...

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“…Betts et al also recently characterized CdsF, the needle filament protein of the C. pneumoniae T3SS (4). C. trachomatis CopN, a homolog of the negative regulator of T3S in other species (that blocks the injectisome channel and is a known effector protein), has recently been shown to be translocated through heterologous T3S systems and may be an effector protein in C. pneumoniae (10,17). Two important T3S genes, however, have not yet been identified in Chlamydia.…”

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confidence: 99%

Characterization of the Putative Type III Secretion ATPase CdsN (Cpn0707) ofChlamydophila pneumoniae

et al. 2008

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Type III secretion (T3S) is utilized by a wide range of gram-negative bacterial pathogens to allow the efficient delivery of effector proteins into the host cell cytoplasm through the use of a syringe-like injectisome. Chlamydophila pneumoniae is a gram-negative, obligate intracellular pathogen that has the structural genes coding for a T3S system, but the functionality of the system has not yet been demonstrated. T3S is dependent on ATPase activity, which catalyzes the unfolding of proteins and the secretion of effector proteins through the injectisome.

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Identification and characterization of secreted effector proteins of Chlamydophila pneumoniae TW183

Cited by 29 publications

References 70 publications

Identification and characterization of a type III secretion system inChlamydophila psittaci

Identification and characterization of a type III secretion system inChlamydophila psittaci

Structure and Protein-Protein Interaction Studies on Chlamydia trachomatis Protein CT670 (YscO Homolog)

Characterization of the Putative Type III Secretion ATPase CdsN (Cpn0707) ofChlamydophila pneumoniae

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