Ancient Origin and Gene Mosaicism of the Progenitor of Mycobacterium tuberculosis

PLoS Pathogens

Philip Supply¹  Michel Fabre²  M. Cristina Gutierrez³  Veronique Vincent³  Bahia Omaïs³  Sylvain Brisse⁴  Magali Marmiesse⁵  Roland Brosch⁵ 

[1] INSERM U629, Institut Pasteur de Lille, Lille, France;Laboratoire de Biologie Clinique, HIA Percy, Clamart, France;Laboratoire de Référence des Mycobactéries, Institut Pasteur, Paris, France;Unité de Biodiversité des Bactéries Pathogènes Emergentes, Institut Pasteur, Paris, France;Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, Paris, France

关键词: Mycobacterium tuberculosis;    Sequence alignment;    Mutant genotypes;    Evolutionary genetics;    Phylogenetics;    Species delimitation;    Africa;    Paleogenetics;   

DOI  :  10.1371/journal.ppat.0010005

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The highly successful human pathogen Mycobacterium tuberculosis has an extremely low level of genetic variation, which suggests that the entire population resulted from clonal expansion following an evolutionary bottleneck around 35,000 y ago. Here, we show that this population constitutes just the visible tip of a much broader progenitor species, whose extant representatives are human isolates of tubercle bacilli from East Africa. In these isolates, we detected incongruence among gene phylogenies as well as mosaic gene sequences, whose individual elements are retrieved in classical M. tuberculosis. Therefore, despite its apparent homogeneity, the M. tuberculosis genome appears to be a composite assembly resulting from horizontal gene transfer events predating clonal expansion. The amount of synonymous nucleotide variation in housekeeping genes suggests that tubercle bacilli were contemporaneous with early hominids in East Africa, and have thus been coevolving with their human host much longer than previously thought. These results open novel perspectives for unraveling the molecular bases of M. tuberculosis evolutionary success.

【 授权许可】

CC BY