Mycolic acid and cholesterol induced transcriptomic adaptations in wild type and Mce complex ATPase subunit deleted strain of <i>M. tuberculosis</i> H37Rv

During infection and latency, Mycobacterium tuberculosis (Mtb) primarily relies on lipids as its main energy source. The Mtb mammalian cell entry (Mce) complexes function as lipid transporters with Mkl as the ATPase subunit for substrate translocation. Cholesterol and mycolic acid are essential to the infectiousness and pathogenicity of Mtb. Here, we have investigated the transcriptomic responses of wild type and ∆mkl strains of Mtb to cholesterol and mycolic acid through RNAseq analysis. The number of differentially expressed genes was always higher when grown on cholesterol than on mycolic acid. In most cases, ∆mkl showed the opposite gene expression pattern compared to the wild type. Among the four mce operons, significant changes in expression patterns were observed mainly in the genes of mce3 and mce4 operons. The upregulation of mce3 operon and the downregulation of mce4 operon in the presence of mycolic acid and cholesterol is intriguing. The transcriptome profile of genes involved in mycolic acid synthesis did not show significant change to either mycolic acid or cholesterol. However, interestingly, both mycolic acid and cholesterol induce upregulation of methyl citrate cycle and dormancy related genes indicating their significance during Mtb persistence and provides insights on Mtb′s adaptive strategies under stress through transcriptional remodelling.