Mycobacterium leprae TN

Mycobacterium leprae TN is a human and animal pathogen causes leprosy .its genome is 3268203 nucleotide long   contain 1605 protein   coding genes   and 50 RNA coding  genes .The genome sequence of a strain of M. leprae, originally isolated in Tamil Nadu and designated TN, has been completed recently. The sequence was obtained by a combined approach, employing automated DNA sequence analysis of selected cosmids and whole-genome 'shotgun' clones. After the finishing process, the genome sequence was found to contain 3,268,203 base pairs (bp), and to have an average G+C content of 57.8%, values much lower than the corresponding values for M. tuberculosis, which are 4, 441,529 bp and 65.6% G+C. There are 1500 genes which are common to both M. leprae and M. tuberculosis. The comparative analysis suggests that both mycobacteria derived from a common ancestor and, at one stage, had gene pools of similar size. Downsizing from a genome of 4.42 Mb, such as that of M. tuberculosis, to one of 3.27 Mb would account for the loss of some 1200 protein coding sequences. There is evidence that many of the genes that were present in the genome of the common ancestor of M. leprae and M. tuberculosis have been lost by recombination in the M.leprae genome.