Disabling a single bacterial enzyme can turn the tide against strains of Enterococcus faecium that shrug off vancomycin, one of medicine's longstanding defences against serious infections. A study published in Nature Communications demonstrates that genetic deletion or pharmacological inhibition of SagA impairs peptidoglycan remodelling in these resistant bacteria and markedly increases their susceptibility to the antibiotic both in lab samples and in living models.
The paper, which appeared online on 16 June 2026, was led by researchers including Kyong T Fam and Pavan Kumar Chodisetti from Scripps Research together with John E Moses from Cold Spring Harbor Laboratory. Their work rests on fundamental insights from chemistry and evolutionary biology rather than any promise of entirely new classes of drugs. By focusing on how bacteria rebuild their cell walls, the team has uncovered a druggable target whose inactivation restores the potency of an approved medicine.
Genetic removal of the sagA gene or chemical blockade of the SagA enzyme disrupts the normal remodelling of peptidoglycan, the mesh-like structure that gives bacterial cells their shape and strength. With this process compromised, vancomycin regains its ability to interfere with cell wall synthesis. The result is that drug concentrations once considered useless against resistant strains become lethal again.
A key element of the approach is the small molecule pghi-4, first identified in 2020. This compound acts as a covalent inhibitor of SagA. When paired with vancomycin, pghi-4 restores the antibiotic's capacity to kill strains of vancomycin-resistant Enterococcus faecium where vancomycin alone fails. The molecule emerged from a library of compounds generated using diversity-oriented clicking chemistry, a method that efficiently explores wide chemical space from simple building blocks.
A press release issued by Cold Spring Harbor Laboratory on 21 July 2026 highlighted the June publication and included statements from John Moses on the origins of the discovery in fundamental chemical research using diversity-oriented clicking to create the compound library that yielded pghi-4.
The findings arrive at a moment when healthcare-associated infections caused by resistant enterococci continue to pose serious risks. Vancomycin has long served as a reliable option against organisms such as MRSA and Clostridium difficile, yet resistance erodes its value. Rather than discard the drug, this research shows how precise interference with one bacterial protein can resurrect its clinical usefulness.