6MNX

Structural basis of impaired hydrolysis in KRAS Q61H mutant

Summary for 6MNX

• Entry DOI: 10.2210/pdb6mnx/pdb
• Descriptor: GTPase KRas, GUANOSINE-5'-TRIPHOSPHATE, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: gtpase kras hydrolysis, hydrolase
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 6
• Total formula weight: 118975.57

Authors

Bera, A.K.,Westover, K.D. (deposition date: 2018-10-03, release date: 2020-04-15, Last modification date: 2023-10-11)

Primary citation

Zhou, Z.W.,Ambrogio, C.,Bera, A.K.,Li, Q.,Li, X.X.,Li, L.,Son, J.,Gondi, S.,Li, J.,Campbell, E.,Jin, H.,Okoro, J.J.,Xu, C.X.,Janne, P.A.,Westover, K.D.
KRASQ61HPreferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non-Small Cell Lung Cancer.
Cancer Res., 80:3719-3731, 2020

PubMed Abstract: Assembly of RAS molecules into complexes at the cell membrane is critical for RAS signaling. We previously showed that oncogenic KRAS codon 61 mutations increase its affinity for RAF, raising the possibility that KRAS, the most common KRAS mutation at codon 61, upregulates RAS signaling through mechanisms at the level of RAS assemblies. We show here that KRAS exhibits preferential binding to RAF relative to PI3K in cells, leading to enhanced MAPK signaling in models and human NSCLC tumors. X-ray crystallography of KRAS:GTP revealed that a hyperdynamic switch 2 allows for a more stable interaction with switch 1, suggesting that enhanced RAF activity arises from a combination of absent intrinsic GTP hydrolysis activity and increased affinity for RAF. Disruption of KRAS assemblies by the RAS oligomer-disrupting D154Q mutation impaired RAF dimerization and altered MAPK signaling but had little effect on PI3K signaling. However, KRAS oligomers but not KRAS oligomers were disrupted by RAF mutations that disrupt RAF-RAF interactions. KRAS cells show enhanced sensitivity to RAF and MEK inhibitors individually, whereas combined treatment elicited synergistic growth inhibition. Furthermore, KRAS tumors in mice exhibited high vulnerability to MEK inhibitor, consistent with cooperativity between KRAS and RAF oligomerization and dependence on MAPK signaling. These findings support the notion that KRAS and functionally similar mutations may serve as predictive biomarkers for targeted therapies against the MAPK pathway. SIGNIFICANCE: These findings show that oncogenic KRAS forms a cooperative RAS-RAF ternary complex, which renders RAS-driven tumors vulnerable to MEKi and RAFi, thus establishing a framework for evaluating RAS biomarker-driven targeted therapies.

PubMed: 32605999
DOI: 10.1158/0008-5472.CAN-20-0448

Experimental method

X-RAY DIFFRACTION (2.2 Å)