title: Identification of a Haarlem genotype-specific single nucleotide polymorphism in the mgtC virulence gene of Mycobacterium tuberculosis.
abstract: MgtC is a virulence factor common to several intracellular pathogens, including Mycobacterium tuberculosis, that might have been acquired through horizontal gene transfer. In the present study, we investigated the polymorphism of mgtC in clinical isolates representative of the main epidemic groups of M. tuberculosis. MgtC appears to have a low polymorphism rate in M. tuberculosis that consists exclusively of nonsynonymous mutations. We identified a single nucleotide polymorphism (SNP) at mgtC codon 182 (mgtC182) specifically associated with the Haarlem genotype. A simple PCR assay, called the "on/off switch assay," using phosphorothioate-modified primers and Pfu polymerase allowed us to distinguish Haarlem from non-Haarlem strains based on the mgtC182 SNP. The amino acid change (H182R) associated with the mgtC182 SNP in Haarlem strains does not appear to procure a selective advantage. Our results offer a simple and rapid tool to distinguish between Haarlem and non-Haarlem strains. In addition, the on/off switch assay, which allows the detection of SNPs on chromosomal DNA and M. tuberculosis cultures, provides a novel approach for the screening of known SNPs in M. tuberculosis.
authors.affiliation: INSERM U431, Avenir Team, UFR de Médecine, CS 83021, Avenue Kennedy, 30908 Nimes Cedex 02, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Alix
authors.forename: Sylvain
authors.initials: S
authors.lastname: Godreuil
authors.forename: Anne-Béatrice
authors.initials: AB
authors.lastname: Blanc-Potard
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D027682:Cation Transport Proteins / Q000235:genetics*; D003062:Codon / Q000235:genetics; D005816:Genetic Complementation Test; D005838:Genotype; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D013045:Species Specificity; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D003062:Codon; D037521:Virulence Factors; C093586:MgtC protein, Salmonella typhimurium