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Identification and Characterization of a Novel Porin Family Highlights a Major Difference in the Outer Membrane of Chlamydial Symbionts and Pathogens

Please always quote using this URN: urn:nbn:de:bvb:20-opus-131176
  • The Chlamydiae constitute an evolutionary well separated group of intracellular bacteria comprising important pathogens of humans as well as symbionts of protozoa. The amoeba symbiont Protochlamydia amoebophila lacks a homologue of the most abundant outer membrane protein of the Chlamydiaceae, the major outer membrane protein MOMP, highlighting a major difference between environmental chlamydiae and their pathogenic counterparts. We recently identified a novel family of putative porins encoded in the genome of P. amoebophila by in silicoThe Chlamydiae constitute an evolutionary well separated group of intracellular bacteria comprising important pathogens of humans as well as symbionts of protozoa. The amoeba symbiont Protochlamydia amoebophila lacks a homologue of the most abundant outer membrane protein of the Chlamydiaceae, the major outer membrane protein MOMP, highlighting a major difference between environmental chlamydiae and their pathogenic counterparts. We recently identified a novel family of putative porins encoded in the genome of P. amoebophila by in silico analysis. Two of these Protochlamydia outer membrane proteins, PomS (pc1489) and PomT (pc1077), are highly abundant in outer membrane preparations of this organism. Here we show that all four members of this putative porin family are toxic when expressed in the heterologous host Escherichia coli. Immunofluorescence analysis using antibodies against heterologously expressed PomT and PomS purified directly from elementary bodies, respectively, demonstrated the location of both proteins in the outer membrane of P. amoebophila. The location of the most abundant protein PomS was further confirmed by immuno-transmission electron microscopy. We could show that pomS is transcribed, and the corresponding protein is present in the outer membrane throughout the complete developmental cycle, suggesting an essential role for P. amoebophila. Lipid bilayer measurements demonstrated that PomS functions as a porin with anion-selectivity and a pore size similar to the Chlamydiaceae MOMP. Taken together, our results suggest that PomS, possibly in concert with PomT and other members of this porin family, is the functional equivalent of MOMP in P. amoebophila. This work contributes to our understanding of the adaptations of symbiotic and pathogenic chlamydiae to their different eukaryotic hosts.show moreshow less

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Metadaten
Author: Karin Aistleitner, Christian Heinz, Alexandra Hoermann, Eva Heinz, Jacqueline Montanaro, Frederik Schulz, Elke Maier, Peter Pichler, Roland Benz, Matthias Horn
URN:urn:nbn:de:bvb:20-opus-131176
Document Type:Journal article
Faculties:Fakultät für Biologie / Rudolf-Virchow-Zentrum
Language:English
Parent Title (English):PLoS ONE
Year of Completion:2013
Volume:8
Issue:1
Pagenumber:e55010
Source:PLoS ONE 8(1): e55010. doi:10.1371/journal.pone.0055010
DOI:https://doi.org/10.1371/journal.pone.0055010
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Tag:cell wall; developmental cycle; escherichia coli; gram negative bacteria; matrix protein porin; monoclonal antibodies; mycobacterium smegmatis; protochlamydia amoebophila; signal peptides; single channel analysis
Release Date:2016/05/12
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung