Regulation of Dormancy-Associated Genes dosR by TetR Family Regulator MRA_0776 in Mycobacterium Tuberculosis H37Ra

The Dormancy survival regulator (DosR), Rv3133c, is one of the key transcriptional proteins that regulate the dormancy of Mycobacterium tuberculosis (MTB), participates in various metabolic processes, and is essential for the survival of MTB in the host. MRA_0776 (homologous with Rv0767c and MSMEG_5860) belongs to the TetR family of regulators; we previously found that MRA_0776 can directly regulate the expression of dosR, although the mechanism by which MRA_0776 acts directly on dosR and other small molecules affecting the interaction of MRA_0776 with dosR has not been elucidated.

In the present study, primary transcriptomic analysis of a MRA_0776 overexpression strain revealed that MRA_0776 is a broad-spectrum regulatory protein and that MRA_0776 specifically binds to the dosR promoter both in vitro and in vivo. In addition, we found that a range of ligands, including lysine, arginine, tyrosine, Cu²⁺, Fe³⁺ and Pb²⁺, inhibited the interaction of MRA_0776 with the dosR promoter. Furthermore, molecular docking predicted that 125-Thr is likely to be a key amino acid site for the interaction of MRA_0776 with ligands. Finally, MRA_0776 promoted bacteria colonization and induced pathological damage in livers, spleens, lungs, and kidneys in mice.

In conclusion, our analyses suggested that MRA_0776 is a pleiotropic regulator, and its overexpression can promote colonization and pathogenicity of MTB.