TitleInclusion membrane proteins of Protochlamydia amoebophila UWE25 reveal a conserved mechanism for host cell interaction among the Chlamydiae.
Publication TypeJournal Article
Year of Publication2010
AuthorsHeinz, E, Rockey, DD, Montanaro, J, Aistleitner, K, Wagner, M, Horn, M
JournalJ Bacteriol
Date Published2010 Oct
KeywordsAcanthamoeba castellanii, Animals, Bacterial Proteins, Blotting, Western, Chlamydia, Membrane Proteins, Microscopy, Immunoelectron

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.

Alternate JournalJ Bacteriol
PubMed ID20675479
PubMed Central IDPMC2944539
Grant ListR01 AI048769 / AI / NIAID NIH HHS / United States
U19 AI031448 / AI / NIAID NIH HHS / United States
AI031448 / AI / NIAID NIH HHS / United States
AI48769 / AI / NIAID NIH HHS / United States