title: Proteome analysis of Rickettsia felis highlights the expression profile of intracellular bacteria.
abstract: The proteome of Rickettsia felis, an obligate intracellular bacterium responsible for spotted fever, was analyzed using two complementary proteomic approaches: 2-DE coupled with MALDI-TOF, and SDS-PAGE with nanoLC-MS/MS. This strategy allowed identification of 165 proteins and helped to answer some questions raised by the genome sequence of this bacterium. We successfully identified potential virulence factors including two putative adhesins, four proteins of the type IV secretion system, four Sca autotransporters, four components of ABC transporters, some R. felis-specific proteins, and one antitoxin of the toxin-antitoxin system. Notably, the antitoxin was the first to be identified in intracellular bacteria. Only one protein containing rickettsia palindromic repeats was found, whereas none of the split genes, transposases, or tetratricopeptide/ankyrin repeats were detectably expressed. Comparison of the protein expression profiles of R. felis and 23 other bacterial species according to functional categories showed that intracellular bacteria express more proteins related to translation, especially ribosomal proteins. However, the remaining bacteria express more proteins related to energy production and carbohydrate/amino acid metabolism. In conclusion, this study reveals R. felis virulence factor expression and highlights the unique protein expression profile of intracellular bacteria.
authors: Unité des Rickettsies, CNRS-UMR 6020, Faculté de Médecine, Université de la Méditerranée, Marseille, France.
authors: Motohiko
authors: M
authors: Ogawa
authors: Patricia
authors: P
authors: Renesto
authors: Saïd
authors: S
authors: Azza
authors: Danielle
authors: D
authors: Moinier
authors: Patrick
authors: P
authors: Fourquet
authors: Jean-Pierre
authors: JP
authors: Gorvel
authors: Didier
authors: D
authors: Raoult
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D015150:Echocardiography, Doppler; D006801:Humans; D008969:Molecular Sequence Data; D020543:Proteome / Q000032:analysis*; D012282:Rickettsia Infections; D041161:Rickettsia felis / Q000737:chemistry* / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D020543:Proteome