Oncogenic mutations Q61L and Q61H confer active form-like structural features to the inactive state (state 1) conformation of H-Ras protein

• Published in: Biochemical and biophysical research communications 2021-08, Vol.565, p.85-90
• Main Authors: Matsumoto, Shigeyuki, Taniguchi-Tamura, Haruka, Araki, Mitsugu, Kawamura, Takashi, Miyamoto, Ryo, Tsuda, Chiemi, Shima, Fumi, Kumasaka, Takashi, Okuno, Yasushi, Kataoka, Tohru
• Format: Article
• Language: English
• Subjects: Crystallography, X-Ray; Guanosine Triphosphate - genetics; Guanosine Triphosphate - metabolism; Humans; Molecular Conformation; Molecular Dynamics Simulation; Mutation; Oncogenic mutant; Proto-Oncogene Proteins p21(ras) - genetics; Proto-Oncogene Proteins p21(ras) - metabolism; Ras; State transition; X-ray crystallography
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2021.05.084

GTP-bound forms of Ras proteins (Ras•GTP) assume two interconverting conformations, “inactive” state 1 and “active” state 2. Our previous study on the crystal structure of the state 1 conformation of H-Ras in complex with guanosine 5’-(β, γ-imido)triphosphate (GppNHp) indicated that state 1 is stabilized by intramolecular hydrogen-bonding interactions formed by Gln61. Since Ras are constitutively activated by substitution mutations of Gln61, here we determine crystal structures of the state 1 conformation of H-Ras•GppNHp carrying representative mutations Q61L and Q61H to observe the effect of the mutations. The results show that these mutations alter the mode of hydrogen-bonding interactions of the residue 61 with Switch II residues and induce conformational destabilization of the neighboring regions. In particular, Q61L mutation results in acquirement of state 2-like structural features. Moreover, the mutations are likely to impair an intramolecular structural communication between Switch I and Switch II. Molecular dynamics simulations starting from these structures support the above observations. These findings may give a new insight into the molecular mechanism underlying the aberrant activation of the Gln61 mutants. •Crystal structures of H-RasQ61L and Q61H in GTP-bound inactive forms were solved.•Switch II of H-RasQ61L in the form exhibited active form-like structural features.•Conformational flexibility of the effector region increased in both of the mutants.•The mutations induced displacement of Asp38 favorable for effector interaction.•These conformational changes may form a basis for activation of the Q61 mutants.