Amplification, cloning and expression of the cytidine triphosphate synthase (CTPS, E.C.6.3.4.2) enzym e from Mycobacterium tuberculosis H37Rv: possible molecular target therapy

Tuberculosis (TB) infection has become a serious worldwide problem, caused by Mycobacterium tuberculosis, infecting a third of the world’s population, acting in synergy with human immunodeficiency virus (HIV) infection. About 30 million people have died from the disease in the past decade and almost 9 million new cases and 2 million deaths occur each year. The emergence of drug resistant isolates of M. tuberculosis, particularly of multidrug resistant TB (MDR-TB), defined as resistant to at least isoniazid and rifampicin, and extensive drug resistant TB (XDR-TB), MDR-TB isolates also resistant to three or more of the six classes of the second-line drugs, imposes a great challenge to public health. The low efficacy of the currently available TB vaccine (BCG), the emergence of MDR strains of M. tuberculosis, and the global spread of HIV (which increases the risk of TB development) are among the factors underlying the ressurgence of TB. New drugs are urgently required to control TB, but the complex biology of M. tuberculosis has hindered the development of novel therapeutic tools. Cytidine triphosphate synthase (CTPS, E.C.6.3.4.2) is encoded by PyrG gene and catalyses the conversion of UTP to CTP. CTPS is an important enzyme for the de novo synthesis of DNA, having a key role in the synthesis of pyrimidines, and can represent a possible molecular target against M. tuberculosis.