KRAS has long been one of cancer biology’s most stubborn molecular targets. The protein acts as a switch that helps cells interpret growth signals, cycling between an active state bound to GTP and an inactive state bound to GDP. Mutations can lock KRAS into a persistently active configuration, driving uncontrolled proliferation in cancers including pancreatic, colorectal, and lung tumors. Now, Wang, Chen, Cao and colleagues report a chemical strategy that tackles an especially difficult class of KRAS mutations: changes at the Q61 position. Their study, published in Nature Chemical Biology, shows that small molecules with Brønsted-basic properties can stimulate GTP hydrolysis in KRAS-Q61 mutant proteins, potentially restoring a reaction that cancer-associated mutations have impaired.
The finding addresses a central problem in RAS-targeted drug discovery. Under normal conditions, KRAS hydrolyzes its bound GTP to GDP, a chemical reaction that turns the signaling switch off. Although KRAS can perform this reaction slowly on its own, cells normally accelerate it using regulatory proteins known as GTPase-activating proteins, or GAPs. The catalytic machinery depends on a precisely positioned water molecule, metal ions, and amino-acid residues that stabilize the negatively charged transition state formed as the phosphate bond is broken. Mutations at Q61 disrupt this arrangement. As a result, the protein remains active for longer, continuously transmitting signals through pathways such as RAF–MEK–ERK and PI3K–AKT.
The Q61 site is particularly important because it sits near the chemical center of the hydrolysis reaction. In the wild-type protein, glutamine at position 61 contributes to the organization of the catalytic water molecule and helps support the transition state. When this residue is replaced by another amino acid, the reaction becomes markedly less efficient, and the mutant protein may also interact poorly with GAPs. Unlike some other KRAS variants, Q61 mutants have not yet yielded a broadly effective direct inhibitor strategy. Their altered catalytic pocket and active-state behavior make it difficult to block signaling with molecules that bind only to one inactive or transient protein conformation.
Rather than attempting simply to occupy a deep pocket on KRAS, the new approach focuses on chemistry. The researchers investigated whether small molecules capable of accepting a proton—a defining property of Brønsted bases—could compensate for the catalytic deficiency created by Q61 mutations. In chemical terms, a base can help remove a proton from water, making the molecule more reactive toward the terminal phosphate of GTP. If the base is positioned correctly near the nucleotide and catalytic metal ions, it could function as an artificial component of the reaction, replacing part of the catalytic assistance normally provided by the protein and its regulatory partners.
Experiments described in the study indicate that selected Brønsted-basic small molecules increase GTP hydrolysis by KRAS proteins carrying Q61 mutations. The effect is significant because it suggests that a drug-like compound does not necessarily need to shut down KRAS by preventing nucleotide binding or occupying a conventional allosteric pocket. It may instead restore the protein’s ability to deactivate itself. This is a form of chemical rescue: the molecule supplies catalytic functionality that the mutated protein has lost. Such a mechanism could, in principle, reduce the time KRAS spends in its signaling-competent, GTP-bound state.
The concept also provides a mechanistic explanation for why ordinary basicity alone is unlikely to be sufficient. A molecule must not only be able to accept a proton; it must also reach the relevant region of KRAS, adopt a productive orientation, and avoid disrupting the protein’s nucleotide-binding architecture. The local electrostatic environment is critical. GTP hydrolysis involves substantial charge redistribution, particularly around the triphosphate group, and the transition state must be stabilized without prematurely displacing the nucleotide. The most useful compounds would therefore combine suitable proton-transfer chemistry with the ability to associate transiently and productively with the KRAS active site.
This strategy is notable because it treats an oncogenic mutation as a catalytic defect rather than merely as a binding-site abnormality. Many successful targeted therapies work by finding a pocket that is created or exposed by a mutation and then blocking the protein’s function. Q61 mutations present a different challenge: they alter the reaction mechanism at the heart of KRAS signaling. By restoring hydrolysis, the new compounds aim to push the protein toward the GDP-bound state instead of competing directly with GTP, which is present at high concentrations inside cells. That distinction could be important for designing inhibitors that remain effective in the nucleotide-rich cellular environment.
The findings may also broaden the range of chemical tools available for studying RAS biology. Compounds that accelerate GTP hydrolysis could help researchers distinguish between effects caused by nucleotide loading, intrinsic catalytic activity, GAP sensitivity, and downstream signal transmission. They may also serve as starting points for structure-guided optimization, provided that future work can improve potency, selectivity, cellular permeability, and metabolic stability. A key challenge will be ensuring that the molecules act on mutant KRAS without triggering unwanted reactions involving other GTPases or cellular enzymes that contain similarly reactive phosphate-containing substrates.
At the same time, the study represents an early chemical advance rather than a demonstrated cancer treatment. Activating hydrolysis in purified protein or biochemical systems does not automatically mean that a compound will suppress tumors in living organisms. Any prospective therapy would need to reach KRAS at adequate concentrations, operate in the crowded and chemically complex cellular environment, and overcome the rapid production and recycling of GTP. Researchers will also need to determine whether mutant cells can evade the intervention by increasing upstream signaling, altering nucleotide metabolism, or activating parallel survival pathways. Nevertheless, the work offers a provocative blueprint: when a cancer mutation breaks a molecular machine’s catalytic cycle, a small molecule may be able to repair the chemistry instead of merely blocking the machine. For one of oncology’s most persistent targets, that shift could open a new chapter in KRAS drug discovery.
Subject of Research: Small-molecule activation of GTP hydrolysis in KRAS-Q61 mutant proteins
Article Title: Brønsted-basic small molecules activate GTP hydrolysis in KRAS-Q61 mutants
Article References: Wang, YC., Chen, SC., Cao, Y. et al. Brønsted-basic small molecules activate GTP hydrolysis in KRAS-Q61 mutants. Nature Chemical Biology (2026). https://doi.org/10.1038/s41589-026-02291-1
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41589-026-02291-1
Keywords: KRAS, KRAS-Q61, GTP hydrolysis, Brønsted bases, small molecules, cancer biology, RAS signaling, chemical catalysis, targeted therapy, oncology
Tags: Brønsted basic small moleculescancer cell proliferation mechanismschemical biology of KRAS mutationschemical strategies for KRAS inhibitionGTP hydrolysis restorationGTPase regulation in cancerKRAS GTP hydrolysis activationKRAS Q61 mutationsmutation-induced KRAS activationRAS-targeted drug discoveryrole of GAPs in KRAS regulationtargeting mutant KRAS in pancreatic and lung cancers
