title: Pangenome and Phylogenomic Analysis of the Pathogenic Actinobacterium Rhodococcus equi.
abstract: We report a comparative study of 29 representative genomes of the animal pathogen Rhodococcus equi The analyses showed that R. equi is genetically homogeneous and clonal, with a large core genome accounting for ≈80% of an isolates' gene content. An open pangenome, even distribution of accessory genes among the isolates, and absence of significant core-genome recombination, indicated that gene gain/loss is a main driver of R. equi genome evolution. Traits previously predicted to be important in R. equi physiology, virulence and niche adaptation were part of the core genome. This included the lack of a phosphoenolpyruvate:carbohydrate transport system (PTS), unique among the rhodococci except for the closely related Rhodococcus defluvii, reflecting selective PTS gene loss in the R. equi-R. defluvii sublineage. Thought to be asaccharolytic, rbsCB and glcP non-PTS sugar permease homologues were identified in the core genome and, albeit inefficiently, R. equi utilized their putative substrates, ribose and (irregularly) glucose. There was no correlation between R. equi whole-genome phylogeny and host or geographical source, with evidence of global spread of genomovars. The distribution of host-associated virulence plasmid types was consistent with the exchange of the plasmids (and corresponding host shifts) across the R. equi population, and human infection being zoonotically acquired. Phylogenomic analyses demonstrated that R. equi occupies a central position in the Rhodococcus phylogeny, not supporting the recently proposed transfer of the species to a new genus.
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Elisa
authors.initials: E
authors.lastname: Anastasi
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Iain
authors.initials: I
authors.lastname: MacArthur
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.|Edinburgh Medical School (Biomedical Sciences), University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Mariela
authors.initials: M
authors.lastname: Scortti
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Sonsiray
authors.initials: S
authors.lastname: Alvarez
authors.affiliation: Department of Large Animal Medicine, University of Georgia, Georgia, USA.
authors.forename: Steeve
authors.initials: S
authors.lastname: Giguère
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom v.boland@ed.ac.uk.|Edinburgh Medical School (Biomedical Sciences), University of Edinburgh, Edinburgh, United Kingdom.|Grupo de Patogenómica Bacteriana, Universidad de Léon, León, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Vázquez-Boland
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D050260:Carbohydrate Metabolism / Q000235:genetics; D019143:Evolution, Molecular; D016680:Genome, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic; D016929:Rhodococcus equi / Q000145:classification / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins
keywords: Actinobacteria; Corynebacteriales; Rhodococcus equi; comparative genomics; genome diversity and evolution; pangenome analysis; phylogenomics