Mutation analysis in Costello syndrome: functional and structural characterization of the HRAS p.Lys117Arg mutation.
Costello syndrome is a mental retardation syndrome characterized by high birth weight, postnatal growth retardation, coarse face, loose skin, cardiovascular problems, and tumor predisposition. De novo heterozygous missense mutations in HRAS codon 12 and 13 disturbing the intrinsic GTP hydrolysis cause Costello syndrome. We report a patient with typical Costello syndrome and a novel heterozygous missense mutation in codon 117 (c.350A>G, p.Lys117Arg) of the HRAS gene, resulting in constitutive activation of the RAS/MAPK pathway similar to the typical p.Gly12Ser and p.Gly12Ala mutations. Recombinant HRAS p.Lys117Arg demonstrates normal intrinsic GTP hydrolysis and responsiveness to GTPase-activating proteins, but the nucleotide dissociation rate is increased 80-fold. Consistent with the biochemical data, the crystal structure of the p.Lys117Arg mutant indicates an altered interaction pattern of the side chain that is associated with unfavorable nucleotide binding properties. Together, these data show that a RAS mutation that only perturbs guanine nucleotide binding has similar functional consequences as mutations that impair GTP hydrolysis and causes human disease.
Denayer
Ellen
E
Department of Human Genetics, Catholic University of Leuven, Leuven, Belgium.
Parret
Annabel
A
Chmara
Magdalena
M
Schubbert
Suzanne
S
Vogels
Annick
A
Devriendt
Koen
K
Frijns
Jean-Pierre
JP
Rybin
Vladimir
V
de Ravel
Thomy J
TJ
Shannon
Kevin
K
Cools
Jan
J
Scheffzek
Klaus
K
Legius
Eric
E
D000015:Abnormalities, Multiple / Q000235:genetics*; D001120:Arginine / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D003062:Codon; D004252:DNA Mutational Analysis; D006153:Guanosine Diphosphate / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007223:Infant; D007231:Infant, Newborn; D008239:Lysine / Q000235:genetics*; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry; D009154:Mutation / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry* / Q000235:genetics*; D013577:Syndrome
D003062:Codon; D050505:Mutant Proteins; D006153:Guanosine Diphosphate; D001120:Arginine; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D008239:Lysine