Figure 2

Proteins of M. tuberculosis are encoded in a way that minimizes the emergence of mononucleotide repeats. The lines depict the ratio between the observed and expected number of mononucleotide repeats (summed over all genes in the genome) as a function of their length. The expected numbers were calculated with a null-model that conserved the amino acid sequence and the gene-specific codon frequencies. The areas comprise 95% of the data from the randomized genomes. For repeats of three (for A, C and G) or six (for T) nucleotides and longer, the lines lie below this area, indicating that such repeats are significantly under-represented.