Variable expression of surface-exposed polymorphic membrane proteins in<i>in vitro</i>-grown<i>Chlamydia trachomatis</i>

Tan, Chun Hong; Hsia, Ru-ching; Shou, Huizhong; Carrasco, Jose Abel Ciprian; Rank, Roger G.; Bavoil, Patrik M.

doi:10.1111/j.1462-5822.2009.01389.x

Cited by 61 publications

(103 citation statements)

References 41 publications

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“…PmpB, PmpC, PmpE, PmpF, PmpG, and PmpH all were significantly enriched in COMC, which is in agreement with previous reports (7,51,63,64,69). Peptides corresponding to these proteins were enriched from approximately 4-fold (PmpC) to 17-fold (PmpG) in the COMC compared to that in the soluble fraction (Table 1).…”

Section: Resultssupporting

confidence: 81%

“…The ␤-barrel domain of ATs (31,71) mediate the translocation of the central and N-terminal domains of these proteins from the periplasm to the bacterial surface; presumably, Pmp proteins are secreted by the same mechanism (72). Eight of nine Pmp proteins predicted from the C. trachomatis serovar L2 genome sequence (60) have been observed in whole EB or COMC and soluble fraction proteomes, and all nine Pmp proteins have been detected in late inclusions by Western blotting (63). However, our results indicated that Pmp proteins differed in their abundance and distribution among EB fractions.…”

Section: Resultsmentioning

confidence: 99%

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Identification ofChlamydia trachomatisOuter Membrane Complex Proteins by Differential Proteomics

Liu¹,

Afrane

Clemmer³

et al. 2010

J Bacteriol

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The extracellular chlamydial infectious particle, or elementary body (EB), is enveloped by an intra-and intermolecular cysteine cross-linked protein shell called the chlamydial outer membrane complex (COMC). A few abundant proteins, including the major outer membrane protein and cysteine-rich proteins (OmcA and OmcB), constitute the overwhelming majority of COMC proteins. The identification of less-abundant COMC proteins has been complicated by limitations of proteomic methodologies and the contamination of COMC fractions with abundant EB proteins. Here, we used parallel liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analyses of Chlamydia trachomatis serovar L2 434/Bu EB, COMC, and Sarkosylsoluble EB fractions to identify proteins enriched or depleted from COMC. All well-described COMC proteins were specifically enriched in the COMC fraction. In contrast, multiple COMC-associated proteins found in previous studies were strongly enriched in the Sarkosyl-soluble fraction, suggesting that these proteins are not COMC components or are not stably associated with COMC. Importantly, we also identified novel proteins enriched in COMC. The list of COMC proteins identified in this study has provided reliable information for further understanding chlamydial protein secretion systems and modeling COMC and EB structures.Bacteria in the phylum Chlamydiae are characterized by their complex intracellular developmental cycles. Chlamydiae must assume at least two functionally distinct morphotypes, the intracellular, replicative reticulate body (RB) and the extracellular, infectious elementary body (EB), to replicate and be transmitted to new hosts (50). The divergence of distinct RB and EB forms may have been driven by the different pressures these pathogens face inside host cells during replication and outside host cells during transmission. For example, the outer membrane of EB contains a poorly immunogenic truncated lipopolysaccharide (LPS) (14, 30) and immunodominant epitopes of the major outer membrane protein (MOMP) vary substantially among closely related chlamydial strains (13). EB also lack detectable peptidoglycan (2, 20, 60), although functional murein biosynthetic enzymes (2,5,16,21,32,43,45,46) are expressed in RB during productive and persistent infection (44). To compensate for the loss of murein, EB are enveloped by a protein P-layer, which lends osmotic stability to the infectious particle (29).Attempts to identify components of the P-layer and outer membrane proteins of Chlamydia were advanced by the observation that these layers can be separated from many soluble EB proteins using the detergent N-lauroyl sarcosine (Sarkosyl). Caldwell et al. dubbed the Sarkosyl-insoluble fraction the chlamydial outer membrane complex (COMC) and noted that purified COMC maintained the shape of intact EB and contained a complete outer membrane, and they reported that a single outer membrane protein, MOMP, accounted for more than 60% of total COMC protein content (15). Other studies revealed that the COMC is ...

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Identification ofChlamydia trachomatisOuter Membrane Complex Proteins by Differential Proteomics

Liu¹,

Afrane

Clemmer³

et al. 2010

J Bacteriol

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“…This suggests that other Pmp proteins might compensate for the loss of PmpD. C. trachomatis pmp genes exhibit phase-variable expression patterns during the chlamydial growth cycle (25). Although the significance of the phase variation is not known, it could represent a potential compensatory mechanism important to chlamydial pathogenesis.…”

Section: Discussionmentioning

confidence: 99%

Chlamydia trachomatis Polymorphic Membrane Protein D Is a Virulence Factor Involved in Early Host-Cell Interactions

et al. 2014

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Chlamydia trachomatis is an obligate intracellular mucosotropic pathogen of significant medical importance. It is the etiological agent of blinding trachoma and bacterial sexually transmitted diseases, infections that afflict hundreds of millions of people globally. The C. trachomatis polymorphic membrane protein D (PmpD) is a highly conserved autotransporter and the target of broadly cross-reactive neutralizing antibodies; however, its role in host-pathogen interactions is unknown. Here we employed a targeted reverse genetics approach to generate a pmpD null mutant that was used to define the role of PmpD in the pathogenesis of chlamydial infection. We show that pmpD is not an essential chlamydial gene and the pmpD null mutant has no detectable deficiency in cultured murine cells or in a murine mucosal infection model. Notably, however, the pmpD null mutant was significantly attenuated for macaque eyes and cultured human cells. A reduction in pmpD null infection of human endocervical cells was associated with a deficiency in chlamydial attachment to cells. Collectively, our results show that PmpD is a chlamydial virulence factor that functions in early host-cell interactions. This study is the first of its kind using reverse genetics to evaluate the contribution of a C. trachomatis gene to disease pathogenesis. Chlamydia trachomatis is an obligate intracellular mucosotropic bacterium that is the most common cause of preventable blindness (1, 2) and bacterial sexually transmitted infections worldwide (3-5). The study of these medically important pathogens has been severely limited in the past by the lack of genetic tools. However, newly developed genetic approaches enable us to ask definitive questions about the contribution of specific chlamydial genes to pathogenesis (6-8). Polymorphic membrane protein D (PmpD) is one of nine putative autotransporters (ATs) encoded in the C. trachomatis genome (9). ATs are members of the Gram-negative bacterial type V secretion system and are important virulence factors that function in host-cell interactions and immune evasion (10). PmpD exhibits classical AT processing resulting in a membrane translocator domain that facilitates the presentation of a passenger domain on the chlamydial surface (11). PmpD is highly conserved among all C. trachomatis strains and is the target of broadly neutralizing antibodies (12). Despite its conserved nature, surface localization, and immunological importance, little is known about the function of PmpD in the pathogenesis of C. trachomatis infection.Here, we made a C. trachomatis pmpD null mutant using a targeted reverse genetic approach (6). pmpD was not essential for C. trachomatis growth, and the pmpD null mutant showed no deficiency in cultured murine cell lines in vitro or in a mouse urogenital infection model. However, the pmpD null mutant was attenuated in cultured human endocervical and conjunctival cells and in a nonhuman primate model of C. trachomatis ocular infection. Our findings show that C. trachomatis PmpD is a virulence fact...

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“…Several Pmps of C. trachomatis, C. pneumoniae, C. psittaci, and C. abortus have been shown to elicit a humoral immune response (13,25), with PmpD of C. trachomatis being described as a pan-neutralizing antigen (26). Pmps are differentially expressed during the chlamydial developmental cycle (27,28) and are therefore suspected to play a role in antigenic diversity and evasion of the host immune response. Pmp21 of C. pneumoniae has been described as an invasion protein that recruits the epidermal growth factor receptor for host cell entry (29).…”

Section: Discussionmentioning

confidence: 99%

Analysis of Humoral Immune Responses to Surface and Virulence-Associated Chlamydiaabortus Proteins in Ovine and Human Abortions by Use of a Newly Developed Line Immunoassay

et al. 2016

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fThe obligate intracellular bacterium Chlamydia abortus is the causative agent of enzootic abortion of ewes and poses a significant zoonotic risk for pregnant women. Using proteomic analysis and gene expression library screening in a previous project, we identified potential virulence factors and candidates for serodiagnosis, of which nine were scrutinized here with a strip immunoassay. We have shown that aborting sheep exhibited a strong antibody response to surface (MOMP, MIP, Pmp13G) and virulence-associated (CPAF, TARP, SINC) antigens. While the latter disappeared within 18 weeks following abortion in a majority of the animals, antibodies to surface proteins persisted beyond the duration of the study. In contrast, nonaborting experimentally infected sheep developed mainly antibodies to surface antigens (MOMP, MIP, Pmp13G), all of which did not persist. We were also able to detect antibodies to these surface antigens in C. abortus-infected women who had undergone septic abortion, whereas a group of shepherds and veterinarians with occupational exposure to C. abortus-infected sheep revealed only sporadic immune responses to the antigens selected. The most specific antigen for the serodiagnosis of human C. abortus infections was Pmp13G, which showed no cross-reactivity with other chlamydiae infecting humans. We suggest that Pmp13G-based serodiagnosis accomplished by the detection of antibodies to virulence-associated antigens such as CPAF, TARP, and SINC may improve the laboratory diagnosis of human and animal C. abortus infections. Chlamydia abortus is an obligate intracellularly replicating zoonotic bacterium that shares a characteristic biphasic developmental cycle with all other members of the family Chlamydiaceae (1). Among chlamydiae affecting humans, Chlamydia trachomatis is the most clinically and epidemiologically relevant as a cause of oculogenital infections, including nongonococcal urethritis and cervicitis, lymphogranuloma venereum, and trachoma. Chlamydia pneumoniae is known to be involved in community-acquired pneumonia, pharyngitis, bronchitis, and sinusitis. In addition, the avian pathogen Chlamydia psittaci has well-documented zoonotic potential, causing human psittacosis (ornithosis), which may present as a generalized and life-threatening pneumonia (2).C. abortus typically occurs in ruminants such as sheep and goats and is the leading cause of enzootic abortion of ewes (EAE) worldwide (3). Even in the absence of elevated abortion rates, the agent was shown to be widespread in German sheep flocks, with 50% of flocks testing PCR positive and 94% harboring seropositive animals (4). Afterbirths and fetuses of abortion cases can contain heavy loads of the pathogen and represent the major source of transmission to susceptible humans and naive ewes, as well as environmental contamination (3). Inhalation of infective aerosols by pregnant women poses the risk of severe infection, including spontaneous abortion, stillbirth, and septicemia (3, 5, 6). However, very little is known about the clinical rel...

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Variable expression of surface-exposed polymorphic membrane proteins inin vitro-grownChlamydia trachomatis

Cited by 61 publications

References 41 publications

Identification ofChlamydia trachomatisOuter Membrane Complex Proteins by Differential Proteomics

Identification ofChlamydia trachomatisOuter Membrane Complex Proteins by Differential Proteomics

Chlamydia trachomatis Polymorphic Membrane Protein D Is a Virulence Factor Involved in Early Host-Cell Interactions

Analysis of Humoral Immune Responses to Surface and Virulence-Associated Chlamydiaabortus Proteins in Ovine and Human Abortions by Use of a Newly Developed Line Immunoassay

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