title: An Ehrlichia chaffeensis tandem repeat protein interacts with multiple host targets involved in cell signaling, transcriptional regulation, and vesicle trafficking.
abstract: Ehrlichia chaffeensis is an obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes forming cytoplasmic membrane-bound microcolonies called morulae. To survive and replicate within phagocytes, E. chaffeensis exploits the host cell by modulating a number of host cell processes, but the ehrlichial effector proteins involved are unknown. In this study, we determined that p47, a secreted, differentially expressed, tandem repeat (TR) protein, interacts with multiple host proteins associated with cell signaling, transcriptional regulation, and vesicle trafficking. Yeast two-hybrid analysis revealed that p47 interacts with polycomb group ring finger 5 (PCGF5) protein, Src protein tyrosine kinase FYN (FYN), protein tyrosine phosphatase non-receptor type 2 (PTPN2), and adenylate cyclase-associated protein 1 (CAP1). p47 interaction with these proteins was further confirmed by coimmunoprecipitation assays and colocalization in HeLa cells transfected with p47-green fluorescent fusion protein (AcGFP1-p47). Moreover, confocal microscopy demonstrated p47-expressing dense-cored (DC) ehrlichiae colocalized with PCGF5, FYN, PTPN2, and CAP1. An amino-terminally truncated form of p47 containing TRs interacted only with PCGF5 and not with FYN, PTPN2, and CAP1, indicating differences in p47 domains that are involved in these interactions. These results demonstrate that p47 is involved in a complex network of interactions involving numerous host cell proteins. Furthermore, this study provides a new insight into the molecular and functional distinction of DC ehrlichiae, as well as the effector proteins involved in facilitating ehrlichial survival in mononuclear phagocytes.
authors.affiliation: Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, usa.
authors.forename: Abdul
authors.initials: A
authors.lastname: Wakeel
authors.forename: Jeeba A
authors.initials: JA
authors.lastname: Kuriakose
authors.forename: Jere W
authors.initials: JW
authors.lastname: McBride
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism; D018469:Ehrlichia chaffeensis / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D009000:Monocytes / Q000382:microbiology; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2 / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D017384:Sequence Deletion; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; C489549:CAP1 protein, human; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D063146:Polycomb-Group Proteins; D011506:Proteins; D012097:Repressor Proteins; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; C516649:PTPN2 protein, human; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2