Cholesterol and fatty acids grease the wheels of Mycobacterium tuberculosis pathogenesis

Tuberculosis is a distinctive disease in which the causative agent, Mycobacterium tuberculosis, can persist in humans for decades by avoiding clearance from host immunity. During infection, M. tuberculosis maintains viability by extracting and utilizing essential nutrients from the host, and this is a prerequisite for all of the pathogenic activities that are deployed by the bacterium. In particular, M. tuberculosis preferentially acquires and metabolizes host-derived lipids (fatty acids and cholesterol), and the bacterium utilizes these substrates to cause and maintain disease. In this review, we discuss our current understanding of lipid utilization by M. tuberculosis, and we describe how these pathways promote pathogenesis to fuel metabolic processes in the bacillus. Finally, we highlight weaknesses in these pathways that potentially can be targeted for drug discovery.