Campus Times | Lucknow 

Researchers at Babasaheb Bhimrao Ambedkar University (BBAU), Lucknow, have identified molecular clues that could help explain how Mycobacterium tuberculosis (Mtb) may reduce the effectiveness of pyrazinamide, a key first-line anti-TB drug.

The study, led by Dr Yusuf Akhter and Prof Dinesh Raj Modi, with PhD researcher Deepti Dhusia, examines Rv0191, a transporter protein belonging to the Major Facilitator Superfamily (MFS). Published in PROTEINS: Structure, Function, and Bioinformatics by Wiley, the research suggests that Rv0191 could act as an efflux transporter, potentially moving pyrazinamide out of the bacterial cell.

Tracking a molecular pump in motion

Rather than examining the transporter as a fixed structure, the BBAU team used molecular docking and long-timescale molecular dynamics simulations to study how Rv0191 changes shape while interacting with pyrazinamide.

The researchers modelled the transporter in different functional states, including outward-open and inward-open conformations. Their simulations point to the protonation state of Glu37—a key residue within Rv0191—as an important factor in triggering structural changes that move the protein towards an intermediate, or occluded, state.

Across triplicate 500-nanosecond simulations, the team observed pyrazinamide interacting with residues in the transporters binding region before moving through a central channel across the membrane. Several loop regions also displayed substantial flexibility, indicating that controlled structural movements may help the transporter regulate the passage of the drug.

The findings suggest that drug efflux may depend not simply on how strongly a drug binds to a transporter, but on the proteins ability to recognise the molecule, accommodate it and subsequently move it through the transport pathway.

A potential target against resistance

The research could offer a new perspective on tackling antimicrobial resistance in TB. Instead of focusing only on developing new antibiotics, scientists could potentially explore ways to inhibit bacterial transporters that remove existing drugs from the cell.

Understanding how the transporter changes its shape and moves the drug can help us identify potential points where its function could be blocked, said Deepti Dhusia, lead author of the study.

Dr Yusuf Akhter, corresponding author, said the work shifts attention towards what happens after a drug binds to a protein—including structural changes and the efficiency of transport.

The authors, however, emphasise that the study is a computational mechanistic framework and a hypothesis for further investigation, rather than experimental confirmation of Rv0191-mediated pyrazinamide efflux. Laboratory studies will be required to establish the transporters role conclusively and determine whether blocking it can improve drug activity.

Significance for drug-resistant TB

The findings come against the backdrop of the continuing global challenge posed by drug-resistant tuberculosis. According to the WHO Global Tuberculosis Report 2025, MDR/RR-TB caused an estimated 150,000 deaths worldwide in 2024. India accounted for the largest share of people developing MDR/RR-TB globally.

While newer all-oral treatment regimens have significantly shortened therapy for drug-resistant TB, resistance mechanisms—including altered drug targets, genetic mutations and potentially drug efflux—continue to complicate treatment.

By providing a molecular picture of how a potential transporter interacts with pyrazinamide, the BBAU study could help guide future experimental research and the search for molecules capable of interfering with bacterial drug-efflux mechanisms.

BBAU Vice Chancellor Prof R K Mittal and Dean of the School Prof Sangeeta Saxena congratulated the research team and encouraged further work in this area.

The study highlights how computational biology can complement laboratory research by revealing dynamic molecular events that are difficult to capture experimentally—and potentially identifying new vulnerabilities in one of the worlds most persistent infectious diseases.