Cloning and overexpression in soluble form of functional shikimate kinase and 5-enolpyruvylshikimate 3-phosphate synthase enzymes from Mycobacterium tuberculosis.

Tuberculosis (TB) resurged in the late 1980s and an estimated 1.87 million people died of TB in 1997. The reemergence of tuberculosis as a public health threat, the high susceptibility of HIV-infected persons, and the proliferation of multidrug-resistant strains have created a need to develop new antimycobacterial agents. The existence of a shikimate pathway has been predicted by the determination of the genome sequence of Mycobacterium tuberculosis. The M. tuberculosis aroK-encoded shikimate kinase and aroA-encoded 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase were cloned and the enzymes overexpressed in soluble form. Overexpression was achieved without isopropyl beta-d-thiogalactoside induction, and cells grown to stationary phase yielded approximately 30% of target proteins to total soluble cell proteins. Enzyme activity measurements using coupled assays demonstrated that there was a 328-fold increase in specific activity for shikimate kinase and 101-fold increase for EPSP synthase.