A KRAS GTPase K104Q Mutant Retains Downstream Signaling by Offsetting Defects in Regulation

J Biol Chem. 2017 Mar 17;292(11):4446-4456. doi: 10.1074/jbc.M116.762435. Epub 2017 Jan 30.


The KRAS GTPase plays a critical role in the control of cellular growth. The activity of KRAS is regulated by guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and also post-translational modification. Lysine 104 in KRAS can be modified by ubiquitylation and acetylation, but the role of this residue in intrinsic KRAS function has not been well characterized. We find that lysine 104 is important for GEF recognition, because mutations at this position impaired GEF-mediated nucleotide exchange. Because the KRAS K104Q mutant has recently been employed as an acetylation mimetic, we conducted a series of studies to evaluate its in vitro and cell-based properties. Herein, we found that KRAS K104Q exhibited defects in both GEF-mediated exchange and GAP-mediated GTP hydrolysis, consistent with NMR-detected structural perturbations in localized regions of KRAS important for recognition of these regulatory proteins. Despite the partial defect in both GEF and GAP regulation, KRAS K104Q did not alter steady-state GTP-bound levels or the ability of the oncogenic KRAS G12V mutant to cause morphologic transformation of NIH 3T3 mouse fibroblasts and of WT KRAS to rescue the growth defect of mouse embryonic fibroblasts deficient in all Ras genes. We conclude that the KRAS K104Q mutant retains both WT and mutant KRAS function, probably due to offsetting defects in recognition of factors that up-regulate (GEF) and down-regulate (GAP) RAS activity.

Keywords: GTPase-activating protein (GAP); Ras protein; guanine nucleotide exchange factor (GEF); nuclear magnetic resonance (NMR); post-translational modification; protein acetylation; signaling; tumorigenesis.

MeSH terms

  • Animals
  • Cells, Cultured
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Guanosine Triphosphate / metabolism*
  • Humans
  • Hydrolysis
  • Mice
  • Models, Molecular
  • Mutation, Missense*
  • NIH 3T3 Cells
  • Point Mutation
  • Protein Conformation
  • Protein Stability
  • Proto-Oncogene Proteins p21(ras) / chemistry
  • Proto-Oncogene Proteins p21(ras) / genetics*
  • Proto-Oncogene Proteins p21(ras) / metabolism*
  • Signal Transduction


  • Guanine Nucleotide Exchange Factors
  • KRAS protein, human
  • Guanosine Triphosphate
  • Hras protein, mouse
  • Proto-Oncogene Proteins p21(ras)

Associated data

  • PDB/4LPK
  • PDB/1NVW
  • PDB/1BKD
  • PDB/1XD2
  • PDB/1WQ1
  • PDB/4GON
  • PDB/1HE8