Biosynthesis and Regulation of Sulfomenaquinone, a Metabolite Associated with Virulence in <i>Mycobacterium tuberculosis</i>

Sulfomenaquinone (SMK) is a recently identified metabolite that is unique to the <i>Mycobacterium tuberculosis</i> (<i>M. tuberculosis</i>) complex and is shown to modulate its virulence. Here, we report the identification of the SMK biosynthetic operon that, in addition to a previously identified sulfotransferase <i>stf3</i>, includes a putative cytochrome P450 gene (<i>cyp128</i>) and a gene of unknown function, <i>rv2269c</i>. We demonstrate that <i>cyp128</i> and <i>stf3</i> are sufficient for the biosynthesis of SMK from menaquinone and <i>rv2269c</i> exhibits promoter activity in <i>M. tuberculosis</i>. Loss of Stf3 expression, but not that of Cyp128, is correlated with elevated levels of menaquinone-9, an essential component in the electron-transport chain in <i>M. tuberculosis</i>. Finally, we showed in a mouse model of infection that the loss of <i>cyp128</i> exhibits a hypervirulent phenotype similar to that in previous studies of the <i>stf3</i> mutant. These findings provide a platform for defining the molecular basis of SMK’s role in <i>M. tuberculosis</i> pathogenesis