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Determining conformational dynamics of the allosteric site in HRas R97G
Author(s) -
Ojeda Monica,
Johnson Christian,
Mattos Carla
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04065
Subject(s) - hras , allosteric regulation , chemistry , gtpase , helix (gastropod) , molecular dynamics , stereochemistry , gtp' , biophysics , biochemistry , mutation , biology , enzyme , computational chemistry , ecology , gene , snail , kras
HRas is a small GTPase that acts as a molecular switch for the Raf/MEK/ERK pathway that leads to cell proliferation, survival, and differentiation. Oncogenic mutations in HRas renders it unable to hydrolyze GTP to GDP, resulting in constitutive activation of HRas and cell proliferation. Additionally, HRas contains an allosteric site that binds Ca 2+ and a negatively charged ligand, promoting helix 3 to shift towards helix 4 and the ordering of switch II. This conformation is associated with intrinsic hydrolysis of HRas in the presence of Raf. Experiments have been performed in our lab to study the effects of point mutations in the allosteric site of HRas on intrinsic hydrolysis constants. When compared to wild‐type, HRas R97G demonstrated increased intrinsic hydrolysis when alone and a significant decrease when in the presence of Raf. Molecular dynamics simulations were utilized to further gain insight on how the dynamics of the allosteric site differed in HRas R97G compared to the wild‐type. These simulations demonstrated increased flexibility in the upper region of helix 3, with greater accessibility to the catalytic conformation for GTP hydrolysis. Support or Funding Information NSF MCB 1244203