scholarly journals Absence of Specific Chlamydia trachomatis Inclusion Membrane Proteins Triggers Premature Inclusion Membrane Lysis and Host Cell Death

Cell Reports ◽  
2017 ◽  
Vol 19 (7) ◽  
pp. 1406-1417 ◽  
Author(s):  
Mary M. Weber ◽  
Jennifer L. Lam ◽  
Cheryl A. Dooley ◽  
Nicholas F. Noriea ◽  
Bryan T. Hansen ◽  
...  
Keyword(s):  
Cell Death ◽  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Host Cell ◽  
Inclusion Membrane ◽  
Host Cell Death ◽  
Membrane Lysis ◽  
Inclusion Membrane Proteins

scholarly journals Characterization of Fifty Putative Inclusion Membrane Proteins Encoded in the Chlamydia trachomatis Genome

2008 ◽  
Vol 76 (6) ◽  
pp. 2746-2757 ◽  
Author(s):  
Zhongyu Li ◽  
Chaoqun Chen ◽  
Ding Chen ◽  
Yimou Wu ◽  
Youmin Zhong ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Chlamydial Infection ◽  
Distribution Patterns ◽  
Western Blot Assay ◽  
Inclusion Membrane ◽  
Urogenital Infection ◽  
Infected Cells ◽  
Inclusion Membrane Proteins

ABSTRACT Although the Chlamydia trachomatis genome is predicted to encode 50 inclusion membrane proteins, only 18 have been experimentally localized in the inclusion membrane of C. trachomatis-infected cells. Using fusion proteins and anti-fusion protein antibodies, we have systematically evaluated all 50 putative inclusion membrane proteins for their localization in the infected cells, distribution patterns, and effects on subsequent chlamydial infection when expressed ectopically, as well as their immunogenicity during chlamydial infection in humans. Twenty-two of the 50 proteins were localized in the inclusion membrane, and 7 were detected inside the inclusions, while the location of the remaining 21 was not defined. Four (CT225, CT228, CT358, and CT440) of the 22 inclusion membrane-localized proteins were visualized in the inclusion membrane of Chlamydia-infected cells for the first time in the current study. The seven intra-inclusion-localized proteins were confirmed to be chlamydial organism proteins in a Western blot assay. Further characterization of the 50 proteins revealed that neither colocalization with host cell endoplasmic reticulum nor inhibition of subsequent chlamydial infection by ectopically expressed proteins correlated with the inclusion membrane localization. Interestingly, antibodies from women with C. trachomatis urogenital infection preferentially recognized proteins localized in the inclusion membrane, and the immunodominant regions were further mapped to the region predicted to be on the cytoplasmic side of the inclusion membrane. These observations suggest that most of the inclusion membrane-localized proteins are both expressed and immunogenic during C. trachomatis infection in humans and that the cytoplasmic exposure may enhance the immunogenicity.

Identification and characterization of a Chlamydia trachomatis early operon encoding four novel inclusion membrane proteins

1999 ◽  
Vol 33 (4) ◽  
pp. 753-765 ◽  
Author(s):  
Marci A. Scidmore-Carlson ◽  
Edward I. Shaw ◽  
Cheryl A. Dooley ◽  
Elizabeth R. Fischer ◽  
Ted Hackstadt
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Inclusion Membrane ◽  
Inclusion Membrane Proteins ◽  
Identification And Characterization

scholarly journals Inclusion Membrane Proteins of Protochlamydia amoebophila UWE25 Reveal a Conserved Mechanism for Host Cell Interaction among the Chlamydiae

2010 ◽  
Vol 192 (19) ◽  
pp. 5093-5102 ◽  
Author(s):  
Eva Heinz ◽  
Daniel D. Rockey ◽  
Jacqueline Montanaro ◽  
Karin Aistleitner ◽  
Michael Wagner ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Host Cell ◽  
Cell Interaction ◽  
Eukaryotic Cell ◽  
Intracellular Bacteria ◽  
Human Pathogens ◽  
Inclusion Membrane ◽  
A Genome ◽  
Inclusion Membrane Proteins ◽  
Host Cell Interaction

ABSTRACT Chlamydiae are a group of obligate intracellular bacteria comprising several important human pathogens. Inside the eukaryotic cell, chlamydiae remain within a host-derived vesicular compartment, termed the inclusion. They modify the inclusion membrane through insertion of unique proteins, which are involved in interaction with and manipulation of the host cell. Among chlamydiae, inclusion membrane proteins have been exclusively found in members of the family Chlamydiaceae, which predominantly infect mammalian and avian hosts. Here, the presence of inclusion membrane proteins in Protochlamydia amoebophila UWE25, a chlamydial endosymbiont of free-living amoebae, is reported. A genome-wide screening for secondary structure motifs resulted in the identification of 23 putative inclusion membrane proteins for this organism. Immunofluorescence analysis demonstrated that five of these proteins were expressed, and four of them could be localized to a halo surrounding the intracellular bacteria. Colocalization studies showed an almost complete overlap of the signals obtained for the four putative inclusion membrane proteins, and immuno-transmission electron microscopy unambiguously demonstrated their location in the inclusion membrane. The presence of inclusion membrane proteins (designated IncA, IncQ, IncR, and IncS) in P. amoebophila shows that this strategy for host cell interaction is conserved among the chlamydiae and is used by chlamydial symbionts and pathogens alike.

scholarly journals Expression and Localization of Predicted Inclusion Membrane Proteins in Chlamydia trachomatis

2015 ◽  
Vol 83 (12) ◽  
pp. 4710-4718 ◽  
Author(s):  
Mary M. Weber ◽  
Laura D. Bauler ◽  
Jennifer Lam ◽  
Ted Hackstadt
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Membrane Microdomains ◽  
Membrane Expression ◽  
Hydrophobic Domain ◽  
Inclusion Membrane ◽  
Content Type ◽  
Genetic Tools ◽  
Type Iii ◽  
Inclusion Membrane Proteins

Chlamydia trachomatisis an obligate intracellular pathogen that replicates in a membrane-bound vacuole termed the inclusion. Early in the infection cycle, the pathogen extensively modifies the inclusion membrane through incorporation of numerous type III secreted effector proteins, called inclusion membrane proteins (Incs). These proteins are characterized by a bilobed hydrophobic domain of 40 amino acids. The presence of this domain has been used to predict up to 59 putative Incs forC. trachomatis; however, localization to the inclusion membrane with specific antibodies has been demonstrated for only about half of them. Here, we employed recently developed genetic tools to verify the localization of predicted Incs that had not been previously localized to the inclusion membrane. Expression of epitope-tagged putative Incs identified 10 that were previously unverified as inclusion membrane localized and thus authentic Incs. One novel Inc and 3 previously described Incs were localized to inclusion membrane microdomains, as evidenced by colocalization with phosphorylated Src (p-Src). Several predicted Incs did not localize to the inclusion membrane but instead remained associated with the bacteria. UsingYersiniaas a surrogate host, we demonstrated that many of these are not secreted via type III secretion, further suggesting they may not be true Incs. Collectively, our results highlight the utility of genetic tools for demonstrating secretion from chlamydia. Further mechanistic studies aimed at elucidating effector function will advance our understanding of how the pathogen maintains its unique intracellular niche and mediates interactions with the host.

scholarly journals Characterization of Host Cell Death Induced by Chlamydia trachomatis

2006 ◽  
Vol 74 (11) ◽  
pp. 6057-6066 ◽  
Author(s):  
Songmin Ying ◽  
Silke F. Fischer ◽  
Matthew Pettengill ◽  
Debye Conte ◽  
Stefan A. Paschen ◽  
...  
Keyword(s):  
Cell Death ◽  
Chlamydia Trachomatis ◽  
Host Cell ◽  
Chlamydial Infection ◽  
Slight Reduction ◽  
Nuclear Condensation ◽  
Apoptotic Pathway ◽  
Host Cell Death ◽  
Nuclear Changes ◽  
Infected Cells

ABSTRACT Chlamydia are obligate intracellular bacteria that modulate apoptosis of the host cell. Strikingly, chlamydial infection has been reported both to inhibit and to induce apoptosis. Although the ability to inhibit apoptosis has been corroborated by the identification of cellular targets, confirmation of cell death induction has been complicated by a mixture of apoptotic features and atypical cell death during infection, as well as by differences in the experimental techniques used to measure cell death. Here we use a panel of well-established approaches in the study of apoptosis to define the form of cell death induced by Chlamydia trachomatis infection. Infected cells displayed apoptotic features such as nuclear condensation and fragmentation, as well as positive TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) staining. Fragmentation of genomic DNA occurred, but was atypical. Clear evidence against the activation of effector caspases was found. Nuclear changes were measured in fibroblasts lacking one or both of the effectors of mitochondrial apoptosis, Bax and Bak. A slight reduction in nuclear changes was observed in Bax-deficient cells and in Bax/Bak double-deficient cells. Most surprisingly, this reduction was almost complete in Bak-deficient cells. Finally, dying infected cells were efficiently taken up by professional phagocytes, suggesting that Chlamydia-induced host-cell death could play a role in the immune response. In conclusion, chlamydial infection can induce cell death. Although Chlamydia-induced cell death has certain morphological features of apoptosis, it does not result from activation of the apoptotic pathway.

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