Cholesterol oxidase is required for virulence of Mycobacterium tuberculosis

Recent reports have indicated that cholesterol plays a crucial role during the uptake of mycobacteria by macrophages. However, the significance of cholesterol modification enzymes encoded by Mycobacterium tuberculosis for bacterial pathogenicity remains unknown. Here, the authors explored whether the well-known cholesterol modification enzyme, cholesterol oxidase (ChoD), is important for virulence of the tubercle bacillus. Homologous recombination was used to replace the choD gene from the M. tuberculosis genome with a nonfunctional copy. The resultant mutant (delta choD) was attenuated in peritoneal macrophages. No attenuation in macrophages was observed when the same strain was complemented with an intact choD gene controlled by a heat shock promoter (delta choDP(hsp)choD). The mice infection experiments confirm the significance of ChoD in the pathogenesis of M. tuberculosis.