Expression, processing, and localization of PmpD of Chlamydia trachomatis Serovar L2 during the chlamydial developmental cycle.
BACKGROUND
While families of polymorphic membrane protein (pmp) genes have been identified in several Chlamydia species, their function remains mostly unknown. These proteins are of great interest, however, because of their location in the outer membrane and possible role in chlamydial virulence.


RESULTS
We analyzed the relative transcription of the pmpD gene, a member of the pmp gene family in C. trachomatis serovar L2, and its protein product translation and processing during the chlamydial developmental cycle. By real-time reverse transcription polymerase chain reaction, the pmpD gene was found to be upregulated at 16 to 24 four hours after infection. Using polyclonal antibodies generated against the predicted passenger domain of PmpD, we demonstrated that it is initially localized on the surface of reticulate bodies, followed by its secretion outside Chlamydia starting at 24 hours after infection. In elementary bodies, we found a approximately 157 kDa PmpD only inside the cell. Both events, the upregulation of pmpD gene transcription and PmpD protein processing and secretion, are coincidental with the period of replication and differentiation of RBs into EBs. We also demonstrated that, in the presence of penicillin, the cleavage and secretion of the putative passenger domain was suppressed.


CONCLUSIONS
Our results are in agreement with the general concept that PmpD is an autotransporter protein which is post-translationally processed and secreted in the form of the putative passenger domain outside Chlamydia at mid- to- late point after infection, coinciding with the development of RBs into EBs.
Kiselev
Andrey O
AO
Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America.
Stamm
Walter E
WE
Yates
John R
JR
Lampe
Mary F
MF
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002690:Chlamydia Infections / Q000378:metabolism* / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity; D003001:Cloning, Molecular; D005455:Fluorescent Antibody Technique; D015964:Gene Expression Regulation, Bacterial; D018507:Gene Expression Regulation, Developmental; D006041:Goats; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001426:Bacterial Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C542391:polymorphic membrane protein D, Chlamydia trachomatis