MT FdR: a ferredoxin reductase from M. tuberculosis that couples to MT CYP51.

We report the molecular cloning, expression and partial characterization of MT FdR, an FAD-associated flavoprotein, from Mycobacterium tuberculosis similar to the oxygenase-coupled NADH-dependent ferredoxin reductases (ONFR). We establish, through kinetic and spectral analysis, that MT FdR preferentially uses NADH as cofactor. Furthermore, MT FdR forms a complex with mycobacterial ferredoxin (MT Fdx) and MT CYP51, a cytochrome P450 (CYP) from M. tuberculosis that is similar to lanosterol 14alpha-demethylase isozymes. This reconstituted system transfers electrons from the cofactor to the heme iron of MT CYP51 and effects the demethylation of lanosterol.