Specifically targeting Mtb cell-wall and TMM transporter: the development of MmpL3 inhibitors.

Tuberculosis (TB) remains a serious threat to whole human health. In particular, the drug resistance of Mycobacterium tuberculosis (Mtb) has become a huge challenge in clinical medicine, and it is extremely urgent to develop effective inhibitors with novel structures and mechanisms. Belonging to the Resistance, Nodulation and Division (RND) superfamily, Mycobacterial membrane proteins Large 3 (MmpL3) is mainly responsible for transporting mycolic acid outside cell membrane to form cell wall, and plays critical roles in iron acquisition which is vital to the survival of Mtb. As a potential Mtb target in recent years, its inhibitor research has attracted wide attention. A series of inhibitors (such as SQ109, AU1235, BM212, etc.) through experimental screening have been reported in succession, especially SQ109 has entered the clinical stage. In this paper, the structural biology information of target MmpL3 was summarized, and the structure-activity relationship (SAR) of inhibitors reported in recent years and their inhibitory mechanism both were reviewed, aiming to provide help for the rational design of MmpL3 inhibitors in the future.