Quantitation of total N⁶-MdA content in M. tuberculosis.

Genomic DNA from the indicated strains was digested to individual nucleosides and methylation content determined by liquid chromatography-coupled tandem mass spectrometry. Results are expressed as the amount of N⁶-MdA per nucleotide (left axis) and percentage of adenines that are methylated in each genome (right axis). Each represents at least three biological replicates. Outliers were removed using Grubbs criteria and error bars represent ± standard deviation. (A) Analysis of the contribution of wildtype and mutant forms of MamA to total adenine methylation levels in strain H37Rv. (B) Analysis of the contributions of MamA and HsdM to total adenine methylation levels in Euro-American (H37Rv) and Beijing (HN878) strain backgrounds.