# Thienopyrimidine amide analogs target MmpL3 in Mycobacterium tuberculosis

## TL;DR

This study shows that thienopyrimidine amide compounds likely target MmpL3, a key protein in the tuberculosis bacteria's cell wall, offering a new approach for drug development.

## Contribution

The paper provides experimental evidence that TPA analogs target MmpL3 in Mycobacterium tuberculosis.

## Key findings

- TPA analogs lost potency against M. tuberculosis strains with MmpL3 mutations.
- TPAs induced cell wall stress and increased ATP production, consistent with MmpL3 inhibition.
- Bacterial cytological profiling showed morphological changes matching known MmpL3 inhibitors.

## Abstract

The identification of novel agents with mechanisms of action distinct from
those currently utilized in tuberculosis treatment remains a significant
challenge. The mycobacterial protein MmpL3 has emerged as a promising drug
target due to its essential role in the synthesis of the cell wall of
Mycobacterium tuberculosis. We previously identified
novel thienopyrimidine amides(TPAs) with good anti-tubercular activity. We
profiled a subset of TPAs, determining activity against intracellular
bacteria and bactericidal activity against replicating bacteria. We ran
assays to determine the mode of action by measuring cell wall stress, ATP
production, and bacterial cytological profiling. We determined activity
against a strain of M. tuberculosis with mutations in MmpL3. We isolated and
sequenced resistant mutants. We tested five analogs against a strain of
M. tuberculosis with mutations in MmpL3 and determined
that they lost potency. Analogs induced PiniBAC, a reporter for
cell wall stress, and led to an ATP boost characteristic of cell wall
inhibitors. Bacterial cytological profiling of a representative compound
revealed a morphological profile consistent with other MmpL3 inhibitors.
Together, our data support MmpL3 as the most probable drug target for the
TPA analogs and add to the growing list of scaffolds that can inhibit this
vulnerable transporter.