FIG 1.

MoCo biosynthetic pathway in M. tuberculosis (adapted from reference 2). MoCo biosynthesis occurs through a highly conserved, four-step pathway. Further modifications of MoCo give rise to alternative forms of the cofactor. A notable feature of this pathway is the multiplicity of homologues involved in the first two steps of the pathway. Genes identified as essential in forward genetic screens are underlined. Parentheses denote genes with weak homology. The moaX gene is reflected twice, since it contains both moaD- and moaE-like domains.