Investigation into the biosynthesis and function of a novel sulfomenaquinone from Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is the leading cause of bacterial deaths worldwide causing two million deaths annually and infects almost one third of the world population. Throughout its lifecycle, Mtb undergoes a series of changes in respiration and metabolic rates. During disease transmission from human to human, the bacteria are in a high respiratory and metabolic rate enabling rapid division. During infection, with the onset of the adaptive immune response, Mtb slows its respiratory and metabolic rates to a non-replicative state. Mtb can persist in this state for years to decades. The delicate balance of the host immune response and Mtb survival is only beginning to be understood. In 2006, we identified a sulfomenaquinone, named S881 for its exact mass, that required the sulfotransferase 3 (stf3) gene for production. A Mtb stf3 mutant exhibited a hypervirulent phenotype in the mouse model of infection. Mice infected with the stf3 mutant, succumbed to infection more rapidly than mice infected with wild type and contained a higher bacterial burden in the lungs. This thesis explores structural characterization of S881 and its biosynthesis and function. Chapter 1 reviews the role of menaquinone, the metabolic precursor to S881, in Mtb, while Chapter 2 discusses the characterization of the S881 structure using high resolution mass spectrometry fragmentation analysis. Chapter 3 discusses the biosynthesis of S881 and investigates the regulation of S881 production. Using the S881 mutants, Chapter 4 explores various models of Mtb infection to study the function of S881. Finally Chapter 5 describes the initial characterization of the promoter for S881 genes to understand S881 genetic regulation