title: The genome of the obligately intracellular bacterium Ehrlichia canis reveals themes of complex membrane structure and immune evasion strategies.
abstract: Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, alpha-proteobacterium, is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). Interesting genome features include a large set of proteins with transmembrane helices and/or signal sequences and a unique serine-threonine bias associated with the potential for O glycosylation that was prominent in proteins associated with pathogen-host interactions. Furthermore, two paralogous protein families associated with immune evasion were identified, one of which contains poly(G-C) tracts, suggesting that they may play a role in phase variation and facilitation of persistent infections. Genes associated with pathogen-host interactions were identified, including a small group encoding proteins (n = 12) with tandem repeats and another group encoding proteins with eukaryote-like ankyrin domains (n = 7).
authors.affiliation: Department of Energy, Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA 94598, USA. Kmavrommatis@lbl.gov
authors.forename: K
authors.initials: K
authors.lastname: Mavromatis
authors.forename: C Kuyler
authors.initials: CK
authors.lastname: Doyle
authors.forename: A
authors.initials: A
authors.lastname: Lykidis
authors.forename: N
authors.initials: N
authors.lastname: Ivanova
authors.forename: M P
authors.initials: MP
authors.lastname: Francino
authors.forename: P
authors.initials: P
authors.lastname: Chain
authors.forename: M
authors.initials: M
authors.lastname: Shin
authors.forename: S
authors.initials: S
authors.lastname: Malfatti
authors.forename: F
authors.initials: F
authors.lastname: Larimer
authors.forename: A
authors.initials: A
authors.lastname: Copeland
authors.forename: J C
authors.initials: JC
authors.lastname: Detter
authors.forename: M
authors.initials: M
authors.lastname: Land
authors.forename: P M
authors.initials: PM
authors.lastname: Richardson
authors.forename: X J
authors.initials: XJ
authors.lastname: Yu
authors.forename: D H
authors.initials: DH
authors.lastname: Walker
authors.forename: J W
authors.initials: JW
authors.lastname: McBride
authors.forename: N C
authors.initials: NC
authors.lastname: Kyrpides
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004283:Dog Diseases / Q000382:microbiology; D004285:Dogs; D041061:Ehrlichia canis / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000472:pathogenicity; D016873:Ehrlichiosis / Q000662:veterinary; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006023:Glycoproteins / Q000235:genetics; D008969:Molecular Sequence Data; D011544:Pseudogenes; D012329:RNA, Bacterial / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006023:Glycoproteins; D012329:RNA, Bacterial