Aug 24, 2013

The role of selection in shaping diversity of natural M. tuberculosis populations

PLoS Pathogens
Caitlin PepperellMarcus W Feldman

Abstract

Mycobacterium tuberculosis (M.tb), the cause of tuberculosis (TB), is estimated to infect a new host every second. While analyses of genetic data from natural populations of M.tb have emphasized the role of genetic drift in shaping patterns of diversity, the influence of natural selection on this successful pathogen is less well understood. We investigated the effects of natural selection on patterns of diversity in 63 globally extant genomes of M.tb and related pathogenic mycobacteria. We found evidence of strong purifying selection, with an estimated genome-wide selection coefficient equal to -9.5 × 10(-4) (95% CI -1.1 × 10(-3) to -6.8 × 10(-4)); this is several orders of magnitude higher than recent estimates for eukaryotic and prokaryotic organisms. We also identified different patterns of variation across categories of gene function. Genes involved in transport and metabolism of inorganic ions exhibited very low levels of non-synonymous polymorphism, equivalent to categories under strong purifying selection (essential and translation-associated genes). The highest levels of non-synonymous variation were seen in a group of transporter genes, likely due to either diversifying selection or local selective sweeps. In addition ...Continue Reading

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  • Citations37

References

Mentioned in this Paper

Mycobacterium canetti
Metabolic Process, Cellular
Establishment and Maintenance of Localization
Methylobacter bovis
Amidophosphoribosyltransferase
Fixed Specimen
Y Chromosome
T-Lymphocyte
Vibrio cholerae
Ribosomal Proteins

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