title: Proteomic screening for possible effector molecules secreted by the obligate intracellular pathogen Coxiella burnetii.
abstract: Coxiella burnetii is a Gram-negative, gamma-proteobacteria with nearly worldwide distribution, and it is the pathogenic agent of Q-fever in man. It is an obligate intracellular parasite that is highly adapted to reside within the eukaryotic phagolysosome. In fact, it is the only known intracellular bacterium that manages to survive and replicate within a fully formed, acidic phagolysosome. C. burnetti possesses a functional Type 4 Secretion System (T4SS), similar to the Dot/Icm system of Legionella pneumophila. Up to date there have been no reports for the effector molecules secreted by Coxiella's T4SS. These are speculated to have quite different roles than the effectors of other intracellular pathogens, since there is no need for phagosomal arrest or escape in the case of Coxiella. In this study, we have investigated the cytoplasm of Vero cells infected with C. burnetti strain Nine Mile Phase II. We have identified by mass spectrometry (ESI-MS/MS) several C. burnetti proteins that bear typical characteristics of effector molecules. Most of the identified proteins were also very alkaline, something which is supportive for a protective strategy that has evolved in this bizarre pathogen against acidic environments.
authors.affiliation: Division of Biochemistry, Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003 Voutes, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Samoilis
authors.forename: Michalis
authors.initials: M
authors.lastname: Aivaliotis
authors.forename: Iosif
authors.initials: I
authors.lastname: Vranakis
authors.forename: Anastasia
authors.initials: A
authors.lastname: Papadioti
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Tselentis
authors.forename: Georgios
authors.initials: G
authors.lastname: Tsiotis
authors.forename: Anna
authors.initials: A
authors.lastname: Psaroulaki
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D016997:Coxiella burnetii / Q000472:pathogenicity / Q000502:physiology*; D003593:Cytoplasm / Q000737:chemistry; D006790:Host-Parasite Interactions; D006863:Hydrogen-Ion Concentration; D010588:Phagosomes; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization; D014709:Vero Cells; D014774:Virulence
chemical_list: D001426:Bacterial Proteins