title: Insights from the complete genome sequence of Mycobacterium marinum on the evolution of Mycobacterium tuberculosis.
abstract: Mycobacterium marinum, a ubiquitous pathogen of fish and amphibia, is a near relative of Mycobacterium tuberculosis, the etiologic agent of tuberculosis in humans. The genome of the M strain of M. marinum comprises a 6,636,827-bp circular chromosome with 5424 CDS, 10 prophages, and a 23-kb mercury-resistance plasmid. Prominent features are the very large number of genes (57) encoding polyketide synthases (PKSs) and nonribosomal peptide synthases (NRPSs) and the most extensive repertoire yet reported of the mycobacteria-restricted PE and PPE proteins, and related-ESX secretion systems. Some of the NRPS genes comprise a novel family and seem to have been acquired horizontally. M. marinum is used widely as a model organism to study M. tuberculosis pathogenesis, and genome comparisons confirmed the close genetic relationship between these two species, as they share 3000 orthologs with an average amino acid identity of 85%. Comparisons with the more distantly related Mycobacterium avium subspecies paratuberculosis and Mycobacterium smegmatis reveal how an ancestral generalist mycobacterium evolved into M. tuberculosis and M. marinum. M. tuberculosis has undergone genome downsizing and extensive lateral gene transfer to become a specialized pathogen of humans and other primates without retaining an environmental niche. M. marinum has maintained a large genome so as to retain the capacity for environmental survival while becoming a broad host range pathogen that produces disease strikingly similar to M. tuberculosis. The work described herein provides a foundation for using M. marinum to better understand the determinants of pathogenesis of tuberculosis.
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia. tim.stinear@med.monash.edu.au
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Stinear
authors.forename: Torsten
authors.initials: T
authors.lastname: Seemann
authors.forename: Paul F
authors.initials: PF
authors.lastname: Harrison
authors.forename: Grant A
authors.initials: GA
authors.lastname: Jenkin
authors.forename: John K
authors.initials: JK
authors.lastname: Davies
authors.forename: Paul D R
authors.initials: PD
authors.lastname: Johnson
authors.forename: Zahra
authors.initials: Z
authors.lastname: Abdellah
authors.forename: Claire
authors.initials: C
authors.lastname: Arrowsmith
authors.forename: Tracey
authors.initials: T
authors.lastname: Chillingworth
authors.forename: Carol
authors.initials: C
authors.lastname: Churcher
authors.forename: Kay
authors.initials: K
authors.lastname: Clarke
authors.forename: Ann
authors.initials: A
authors.lastname: Cronin
authors.forename: Paul
authors.initials: P
authors.lastname: Davis
authors.forename: Ian
authors.initials: I
authors.lastname: Goodhead
authors.forename: Nancy
authors.initials: N
authors.lastname: Holroyd
authors.forename: Kay
authors.initials: K
authors.lastname: Jagels
authors.forename: Angela
authors.initials: A
authors.lastname: Lord
authors.forename: Sharon
authors.initials: S
authors.lastname: Moule
authors.forename: Karen
authors.initials: K
authors.lastname: Mungall
authors.forename: Halina
authors.initials: H
authors.lastname: Norbertczak
authors.forename: Michael A
authors.initials: MA
authors.lastname: Quail
authors.forename: Ester
authors.initials: E
authors.lastname: Rabbinowitsch
authors.forename: Danielle
authors.initials: D
authors.lastname: Walker
authors.forename: Brian
authors.initials: B
authors.lastname: White
authors.forename: Sally
authors.initials: S
authors.lastname: Whitehead
authors.forename: Pamela L C
authors.initials: PL
authors.lastname: Small
authors.forename: Roland
authors.initials: R
authors.lastname: Brosch
authors.forename: Lalita
authors.initials: L
authors.lastname: Ramakrishnan
authors.forename: Michael A
authors.initials: MA
authors.lastname: Fischbach
authors.forename: Julian
authors.initials: J
authors.lastname: Parkhill
authors.forename: Stewart T
authors.initials: ST
authors.lastname: Cole
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D002473:Cell Wall / Q000737:chemistry; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial / Q000235:genetics*; D023281:Genomics; D008969:Molecular Sequence Data; D019910:Mycobacterium marinum / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins