title: Functional interaction between type III-secreted protein IncA of Chlamydophila psittaci and human G3BP1.
abstract: Chlamydophila (Cp.) psittaci, the causative agent of psittacosis in birds and humans, is the most important zoonotic pathogen of the family Chlamydiaceae. These obligate intracellular bacteria are distinguished by a unique biphasic developmental cycle, which includes proliferation in a membrane-bound compartment termed inclusion. All Chlamydiaceae spp. possess a coding capacity for core components of a Type III secretion apparatus, which mediates specific delivery of anti-host effector proteins either into the chlamydial inclusion membrane or into the cytoplasm of target eukaryotic cells. Here we describe the interaction between Type III-secreted protein IncA of Cp. psittaci and host protein G3BP1 in a yeast two-hybrid system. In GST-pull down and co-immunoprecipitation experiments both in vitro and in vivo interaction between full-length IncA and G3BP1 were shown. Using fluorescence microscopy, the localization of G3BP1 near the inclusion membrane of Cp. psittaci-infected Hep-2 cells was demonstrated. Notably, infection of Hep-2 cells with Cp. psittaci and overexpression of IncA in HEK293 cells led to a decrease in c-Myc protein concentration. This effect could be ascribed to the interaction between IncA and G3BP1 since overexpression of an IncA mutant construct disabled to interact with G3BP1 failed to reduce c-Myc concentration. We hypothesize that lowering the host cell c-Myc protein concentration may be part of a strategy employed by Cp. psittaci to avoid apoptosis and scale down host cell proliferation.
authors.affiliation: Department of Cell and Molecular Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Jena, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Borth
authors.forename: Katrin
authors.initials: K
authors.lastname: Litsche
authors.forename: Claudia
authors.initials: C
authors.lastname: Franke
authors.forename: Konrad
authors.initials: K
authors.lastname: Sachse
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Saluz
authors.forename: Frank
authors.initials: F
authors.lastname: Hänel
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D002691:Chlamydophila psittaci / Q000472:pathogenicity*; D004265:DNA Helicases; D054884:Host-Pathogen Interactions; D006801:Humans; D010750:Phosphoproteins / Q000378:metabolism / Q000502:physiology*; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C094163:IncA protein, bacteria; C489427:MYC protein, human; D010750:Phosphoproteins; D000075223:Poly-ADP-Ribose Binding Proteins; D016271:Proto-Oncogene Proteins c-myc; D000067776:RNA Recognition Motif Proteins; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases