Rao et al., "The human mutator gene
homolog MSH2 and its association with hereditary nonpolyposis colon cancer," Cell, vol.
miami.edu/EcoGene/EcoWeb) they focused on were the principal mediators of the SOS response, recA (recombinase gene A, locator EC10823) and lexA (lambda excision gene A, locator EC10533); genes with known involvement in the SOS response, ssb (single strand binding gene, locator EC10976), reef (recombinase gene F, locator ECI0828), dinI (damage inducible gene I, locator EC 12670), umuDC (UV mutator gene
, locator EC11057); and three sigma factor genes whose function in SOS response is not clearly identified, rpoD (RNA polymerase factor subunit D, locator EC10896), rpoH (RNA polymerase factor subunit H, locator EC10897), and WoS (RNA polymerasc f~actor subunit S, locator EC10510).
The human mutator gene
homologue MSH2 and its association with hereditary nonpolyposis colon cancer.
Mutations in putative mutator genes
of Mycobacterium tuberculosis strains of the W-Beijing family.
Transposable elements as mutator genes
Typical ("modem" [8,9]) Beijing strains, including W strains (7), exhibit highly similar, multicopy insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) patterns and have alterations in putative mutator genes
tuberculosis mutator genes mutT1, mutT2, mutT3, and ogt were investigated with the same protocol reported by Rad et al.
Alterations within DNA repair genes (mutator genes) are thought to favor the emergence of MDR strains with an increased adaptability (12).
However, recent findings indicated that exclusively in Beijing genotype strains, mutations are present in putative mutator genes
Recently, Beijing genotype bacteria were reported to carry mutations in putative mutator genes
, which may explain a higher adaptability of these bacteria under stress conditions such as exposure to the intracellular environment or anti-TB drugs (13).
The W-Beijing phylogenetic lineage probably acquired the mutation on codon 48 of the mutT4 only once and before other mutations associated with the mutator genes we describe.
These mutations associated with mutator genes provide a reliable tool for the identification of W-Beijing isolates and thus a useful marker for strains endowed with capacity to yield epidemics.