A team of scientists has identified an enzyme called PurF as a new drug target for tuberculosis, offering a fresh line of attack against a disease that kills more than a million people each year. The finding, published in Nature, shows that a small molecule designated JNJ-6640 can selectively block PurF and halt the growth of Mycobacterium tuberculosis in laboratory and animal models. The discovery arrives alongside a wave of parallel research into other vulnerable points in the TB bacterium, raising the prospect that combination therapies built around these targets could shorten treatment and overcome drug resistance.
Why Purine Biosynthesis Matters
Tuberculosis bacteria depend on a metabolic process called de novo purine biosynthesis to build the molecular building blocks of DNA and RNA. PurF, formally known as amidophosphoribosyltransferase, catalyzes the first committed step in that pathway. Block PurF, and the bacterium loses access to purines it cannot scavenge efficiently from its human host. That asymmetry is what makes the enzyme attractive: human cells rely heavily on salvage pathways and are far less dependent on de novo synthesis, which in principle allows a PurF inhibitor to starve the pathogen without poisoning the patient.
JNJ-6640 is the first compound shown to exploit this vulnerability. Described as a first-in-class PurF inhibitor, the small molecule demonstrated selectivity for the bacterial enzyme in biochemical assays and reduced bacterial burden in mouse infection models. No human pharmacokinetic data have been reported yet, so the compound remains at a preclinical stage. Still, the identification of an entirely previously unexplored TB drug target is significant on its own, because the existing arsenal of frontline drugs hits only a handful of bacterial processes, and resistance to those drugs is spreading.
Mechanistically, PurF sits at the gateway between nitrogen metabolism and nucleotide production, using glutamine as an amide donor to convert phosphoribosyl pyrophosphate into phosphoribosylamine. Inhibiting that step quickly depletes intracellular purine pools, slowing replication and ultimately killing actively dividing bacilli. Because latent TB bacteria divide slowly and may draw on host-derived nutrients, PurF inhibition will likely need to be combined with agents that hit other pathways, but it adds a much-needed new dimension to the therapeutic toolbox.
A Second Target: The Cell Wall Enzyme Pks13
PurF is not the only new vulnerability drawing attention. A separate Nature study validated polyketide synthase 13 as a high-value target by showing that an irreversible covalent inhibitor called CMX410 can disable the enzyme. Pks13 is essential for mycolic-acid cell wall biosynthesis, the waxy outer armor that makes TB notoriously hard to kill. The paper presented structural biology evidence, resistance and target-specificity data, and efficacy signals that included combination effects with other agents.
The structural work behind CMX410 relied on X-ray crystallography performed at the Advanced Light Source at Lawrence Berkeley National Laboratory. Diffraction data collected there allowed researchers to map exactly how CMX410 binds to Pks13, information that could guide the design of next-generation analogs with improved drug-like properties. The use of a sulfur-fluoride exchange chemistry platform to build an irreversible inhibitor is itself a notable design choice, because covalent drugs can maintain target engagement longer than reversible competitors, though they also carry a higher bar for safety testing.
Targeting the mycolic-acid layer is a proven strategy: isoniazid and ethionamide, two long-standing TB drugs, also interfere with cell wall synthesis. However, they act through prodrug activation and can be undermined by resistance mutations in activating enzymes. By contrast, a direct Pks13 inhibitor attacks a different point in the pathway and could retain activity against strains that have escaped older drugs. If CMX410 or related molecules can be optimized for oral dosing and tolerability, they might anchor new backbone regimens for both drug-susceptible and resistant TB.
Reducing Toxicity in Existing Drug Classes
While PurF and Pks13 represent genuinely new targets, another line of research is refining a proven mechanism. Linezolid, an oxazolidinone antibiotic, has become a key part of regimens for drug-resistant TB, but its use is limited by serious side effects including bone marrow suppression and nerve damage. A third Nature-family paper describes MK-7762, a new oxazolidinone (also tracked under the identifier TBD09) engineered to retain anti-TB activity while reducing the toxicity and off-target effects that plague linezolid. MK-7762 is more accurately described as a drug candidate than a novel target, but it addresses one of the most pressing practical barriers in TB care: patients abandoning treatment because they cannot tolerate the drugs.
Preclinical work suggests that MK-7762 preserves potent inhibition of bacterial protein synthesis while showing a reduced impact on mitochondrial translation, a key driver of linezolid’s hematologic and neurologic toxicity. If those advantages hold up in clinical trials, the compound could become a safer building block for all-oral, shorter regimens, especially for multidrug-resistant and extensively drug-resistant disease where therapeutic options are narrow and side effects are common.
The urgency for better tolerated drugs is underscored by epidemiological data. A 2020 review in Future Microbiology reported that 1.2 million people died of tuberculosis in 2018. That toll has not meaningfully declined in the years since, and drug-resistant strains continue to erode the effectiveness of standard six-month regimens. Evidence from landmark trials such as Nix-TB, ZeNix and TB-PRACTECAL has reshaped treatment guidelines for resistant disease, but those regimens still rely on a thin roster of drugs. Each new target or improved compound widens the options available to clinicians assembling combination therapies.
Emerging Targets Beyond Metabolism
The focus on metabolic enzymes like PurF is part of a broader push to map every exploitable weakness in Mycobacterium tuberculosis. Researchers at the University of Sydney recently described the ClpC1–ClpP1P2 protease complex as an underexplored and promising TB drug target, using a proteome-scale approach to characterize how compounds disrupt the bacterium’s protein-recycling machinery. By degrading misfolded or regulatory proteins, this ATP-dependent system helps the pathogen survive stress; blocking it can trigger a lethal accumulation of damaged proteins and disturb key signaling circuits.
Other work is probing how to rejuvenate older drug classes through rational combinations. A recent preclinical study evaluated ethionamide together with a booster molecule called alpibectir, showing that co-administration can enhance activation of ethionamide and restore potency against strains with partial resistance. Investigators reported that the ethionamide–alpibectir pair is moving toward clinical testing as part of multidrug regimens, illustrating how pharmacologic “rescue” strategies can extend the useful life of existing agents while truly novel targets progress through the pipeline.
Taken together, these efforts reflect a diversification of TB drug discovery. Rather than betting on a single magic bullet, researchers are assembling a portfolio of approaches: metabolic chokepoints like PurF, structural vulnerabilities such as Pks13, safer analogs of proven scaffolds like oxazolidinones, and stress-response systems including ClpC1–ClpP1P2. The long-term vision is to combine these in ways that hit the bacterium from multiple angles, lower the risk of resistance, and compress treatment from many months to something closer to the weeks-long courses used for other bacterial infections.
From Bench to Bedside
Despite the scientific momentum, major translational hurdles remain. Compounds such as JNJ-6640 and CMX410 must demonstrate not only potency and selectivity but also favorable pharmacokinetics, penetration into the lung lesions where TB bacilli hide, and safety in prolonged dosing. TB treatment typically lasts at least four months even with the most modern regimens, meaning that even modest toxicities can accumulate. Regulatory pathways for TB drugs can also be complex, because new agents are almost always developed as parts of combinations rather than as stand-alone therapies.
Financing is another constraint. TB predominantly affects low- and middle-income countries, limiting the commercial incentives for large pharmaceutical companies to invest in late-stage development. Public–private partnerships, philanthropic funding and multilateral initiatives have become essential to move promising candidates from early discovery into phase 2 and phase 3 trials. Ensuring that new drugs remain affordable and accessible once approved will require careful attention to licensing, manufacturing and procurement strategies.
Even so, the convergence of structural biology, medicinal chemistry and systems-level microbiology is beginning to pay off. High-resolution enzyme structures, fragment-based screening and covalent chemistry platforms are revealing pockets and reaction mechanisms that were invisible a decade ago. At the same time, global clinical networks are better equipped to test novel regimens rapidly and to detect emerging resistance patterns early.
If the new wave of TB drug targets can be translated into safe, effective regimens, the impact could be profound: shorter, simpler courses for drug-susceptible disease; more reliable cures for resistant infections; and a reduced risk that patients will abandon treatment and seed future outbreaks. For now, PurF, Pks13, ClpC1–ClpP1P2 and refined oxazolidinones remain pieces of a still-forming puzzle. But together they mark a shift from incremental tweaks of mid-20th-century drugs toward a genuinely modern, mechanism-based strategy for one of humanity’s oldest scourges.
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*This article was researched with the help of AI, with human editors creating the final content.
