Abstract
BackgroundChlamydia trachomatis is an obligate intracellular human pathogen causing ocular and urogenital infections that are a significant clinical and public health concern. This bacterium uses a type III secretion (T3S) system to manipulate host cells, through the delivery of effector proteins into their cytosol, membranes, and nucleus. In this work, we aimed to find previously unidentified C. trachomatis T3S substrates.ResultsWe first analyzed the genome of C. trachomatis L2/434 strain for genes encoding mostly uncharacterized proteins that did not appear to possess a signal of the general secretory pathway and which had not been previously experimentally shown to be T3S substrates. We selected several genes with these characteristics and analyzed T3S of the encoding proteins using Yersinia enterocolitica as a heterologous system. We identified 23 C. trachomatis proteins whose first 20 amino acids were sufficient to drive T3S of the mature form of β-lactamase TEM-1 by Y. enterocolitica. We found that 10 of these 23 proteins were also type III secreted in their full-length versions by Y. enterocolitica, providing additional support that they are T3S substrates. Seven of these 10 likely T3S substrates of C. trachomatis were delivered by Y. enterocolitica into host cells, further suggesting that they could be effectors. Finally, real-time quantitative PCR analysis of expression of genes encoding the 10 likely T3S substrates of C. trachomatis showed that 9 of them were clearly expressed during infection of host cells.ConclusionsUsing Y. enterocolitica as a heterologous system, we identified 10 likely T3S substrates of C. trachomatis (CT053, CT105, CT142, CT143, CT144, CT161, CT338, CT429, CT656, and CT849) and could detect translocation into host cells of CT053, CT105, CT142, CT143, CT161, CT338, and CT429. Therefore, we revealed several C. trachomatis proteins that could be effectors subverting host cell processes.
Highlights
Chlamydia trachomatis is an obligate intracellular human pathogen causing ocular and urogenital infections that are a significant clinical and public health concern
Selection of C. trachomatis proteins analyzed in this work To search for previously unidentified T3S substrates of C. trachomatis, we first surveyed the genome of strain L2/434 for genes encoding mostly uncharacterized proteins, or with a putative biochemical activity compatible with the function of a T3S effector
We selected those encoding proteins not predicted to have a signal sequence characteristic of the general secretory pathway and that had not been previously analyzed experimentally for the presence of a T3S signal. This singled out 32 proteins (CT016, CT017, CT031, CT051, CT053, CT080, CT105, CT142, CT143, CT144, CT153, CT161, CT172, CT273, CT277, CT289, CT309, CT330, CT338, CT386, CT425, CT568, CT583, CT590, CT631, CT635, CT656, CT696, CT702, CT837, CT845, and CT849; we used the nomenclature of the annotated C. trachomatis D/UW3 strain [53]; the names of the corresponding genes as annotated for strain L2/434 [54] can be found in Additional file 3: Table S3)
Summary
Chlamydia trachomatis is an obligate intracellular human pathogen causing ocular and urogenital infections that are a significant clinical and public health concern. This bacterium uses a type III secretion (T3S) system to manipulate host cells, through the delivery of effector proteins into their cytosol, membranes, and nucleus. Throughout its developmental cycle, C. trachomatis uses a type III secretion system (T3SS) to translocate several effector proteins across the host cell plasma membrane and the inclusion membrane [4,5]. There are, chlamydial effectors, such as CPAF/CT858 or CT441, which are not T3S substrates [4]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
