How KRAS Mutations Impair Intrinsic GTP Hydrolysis: Experimental and Computational Investigations.

Area of Science:

• Molecular Biology
• Biochemistry
• Cancer Research

Background:

• Oncogenic KRAS mutations promote cancer by increasing the active GTP-bound KRAS population.
• Current KRAS inhibitors often target the inactive GDP-bound form, limited by slow GTP hydrolysis.
• Improved understanding of impaired hydrolysis mechanisms is vital for advanced therapeutic design.

Purpose of the Study:

• Investigate how key oncogenic KRAS mutations impact intrinsic GTP hydrolysis.
• Elucidate the mechanistic basis for impaired GTP hydrolysis in mutant KRAS.
• Inform the development of novel small-molecule inhibitors and therapeutic strategies.

Main Methods:

• Employed a combination of experimental and computational approaches.
• Assessed the effect of specific KRAS mutations (Q61H, G12V, G12R, G12A, G12C, G12D, G13D) on GTP hydrolysis rates.
• Performed mechanistic investigations into the molecular interactions affecting hydrolysis.

Main Results:

• Q61H, G12V, and G12R mutations significantly impaired intrinsic GTP hydrolysis (7-fold, 9-fold, and >20-fold, respectively).
• Mutations G12A, G12C, G12D, and G13D showed less impact on hydrolysis rates.
• Proposed that mutations disrupt the alignment of water molecules necessary for GTP hydrolysis.

Conclusions:

• KRAS mutations differentially impair intrinsic GTP hydrolysis, with Q61H, G12V, and G12R being particularly detrimental.
• The mechanism involves disruption of critical interactions for nucleophilic attack on GTP.
• Findings provide a mechanistic basis for designing improved KRAS-targeted cancer therapies, including hydrolysis-rescuing strategies.