[Transcription regulation in the ribosomal RNA operon of mycobacteria]

Tuberculosis is a extremely important infectious disease, caused by the bacilli Mycobacterium tuberculosis. One of the characteristic of this bacteria is its very slow rate of growth, that allows it to survive for long periods of time inside the host cells. Among the genetic elements involved in growth regulation the operon rrn is of extreme importance. This operon contains the genes that code the three rRNA molecules, essential components of the bacterial ribosome. The tuberculosis bacilli, differently from most of the microorganisms, has a single copy of the rrn operon per genome, meaning that it must be submitted to very strict control mechanisms. Another important conclusion is that the sequences of the rrn operon constitute ideal targets for anti-mycobacterial drugs. In this work we have studied some of the elements involved in transcription control in M. tuberculosis, particularly those present in the leader region of the operon. By using basic molecular biology techniques we have identified sequence elements in the leader region that seem to be involved in the control of transcription elongation, by a mechanism related to anti-termination.