The development of rifampicin-resistance strains of Mycobacterium tuberculosis (Mtb) has resulted in imperative need for development of analogs of rifamycin. The endless efforts by genetic manipulation of rifamycin biosynthetic gene cluster of Amycolatopsis mediterranei S699 has led to discovery of a new anti-tuberculosis drug, 24-desmethylrifamycin B, more effective against rifampicinresistance strains of Mtb. The mutant strain A. mediterranei DCO#34 had undergone substitution of acyltransferase domain of module 6 of rifamycin polyketide synthase with that of module 2 of rapamycin polyketide synthase. Genetic manipulation resulted in reduced yield of analog ~20mg/litre as compared to 50mg/l yield by the wild type strain. In order to decipher the impact of domain swapping on rifamycin/analog production, and the intricate make-up and clinical importance of rifamycin brought up the idea to study the regulation of rifamycin biosynthesis, stateof- the-art protein expression methodologies were carried out.
