New transporter gene linked to rifampin tolerance in tuberculosis

Tuberculosis remains a stubborn global health problem because the bacterium that causes it, Mycobacterium tuberculosis, can survive long antibiotic courses and sometimes tolerate drugs without being genetically resistant. That tolerance helps infections linger and lengthens treatment, creating opportunities for true drug resistance to develop. In new research led by corresponding author Petros C. Karakousis, scientists focused on a specific bacterial transporter gene, pstA1, to understand its role in helping M. tuberculosis survive therapy. The team investigated how loss or alteration of this phosphate-specific transport system affects the bacteria’s behavior during treatment, and they tracked broad changes in bacterial gene activity. Their work looked beyond single resistance mutations to examine tolerance mechanisms—cellular programs that let bacteria persist when exposed to antibiotics. By homing in on pstA1/PstA1, Karakousis and colleagues asked whether targeting a transporter could make standard drugs work faster and reduce the time patients need to stay on therapy.

The researchers observed substantial transcriptional reprogramming associated with changes in the transporter, noting 58 differentially expressed genes. Those changes included altered expression of metabolic, DNA damage repair, and secretory pathways, indicating that pstA1/PstA1 influences many parts of bacterial physiology. Crucially, the study reports that bacteria lacking the transporter are eliminated more rapidly by rifampin, demonstrating that this transporter actively promotes bacterial survival during treatment. From these results, the authors conclude that PstA1 represents a novel drug target. The findings suggest that inhibitors of PstA1 could be developed as adjunctive therapies to combine with standard antibiotics such as rifampin, with the aim of accelerating bacterial clearance and shortening treatment courses.

If drugs targeting PstA1 can be created and safely combined with existing antibiotics, they could change how tuberculosis is treated. Shorter regimens would reduce the burden on patients and health systems and could improve adherence to therapy, which is critical to preventing the emergence of drug-resistant disease. By attacking tolerance mechanisms rather than only killing bacteria through conventional antibiotic targets, adjunctive therapies aimed at PstA1 could reduce the number of surviving bacteria during treatment windows when resistance can arise. The authors emphasize that targeting a transporter like PstA1 offers a complementary strategy to existing drugs: rather than replacing rifampin or other frontline antibiotics, PstA1 inhibitors could make those drugs more effective, hastening clearance of Mycobacterium tuberculosis and helping to lower the global burden of drug-resistant tuberculosis.