Using a heterologous DNA gyrase probe from Streptomyces sphaeroides, we have cloned the gyrA and gyrB genes of Mycobacterium tuberculosis. The M. tuberculosis gyrB gene has been sequenced and compared with the amino acid sequences of GyrB from other bacteria. There is a significant level (60-80%) of amino acid sequence homology between GyrB of M tuberculosis and that of other bacterial species, indicating a high degree of conservation of this essential enzyme
