A evolutionary scenario for de DR region in M. tuberculosis complex

CAIMI, K; ROMANO, M; SANTANGELO, P.; ALITO, A; GIOFFRE, A; BIGI, F; KLEPP, L; ZUMARRAGA, M; CATALDI, A.

Villa Carlos Paz, Córdoba

Congreso; XXXVIII Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2002

Sociedad Argentina de Investigaciones Bioquímicas (SAIB)

The direct repeat region in Mycobacterium tuberculosis complex is composed by  multiple 36-bp direct repeat (DR) separated by non-repetitive spacers. Different isolates show extensive polymorphism in the DR region by the variable presence of 36bp-spacers units. This polymorphism has been used in tuberculosis epidemiology by applying a reverse line hybridization method called spoligotyping, that uses a membrane with a 43 randomly selected spacers. We described novel spacers in Mycobacterium bovis. Interestingly some of these spacers are present in M. bovis and absent in M. tuberculosis. We present here the utilization of a novel membrane that contain 104 spacers. Instead of using spoligotyping for typing we used it to understand the evolutionary scenario leading to polymorphic DR loci and to mycobacterial spetiation. We submitted to 104-spoligotyping, DNA from different strains of Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium microti and mycobacterial isolates seals. The probable molecular events that lead to the actual structure of DR region in some strains could be inferred. We also analyze the presence of particular set of spacers that are markers of a given species. It is assumed that the 36 bp and spacers units tend to be lost during evolution, then the presumptive derivative relationship among strains can be hypothesized. Also the structure of DR region in other mycobacterial species is presented.