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Biochemical and structural characterization of two variants of uncertain significance in the PMS2 gene
Author(s) -
D'Arcy Brandon M.,
Blount Jessa,
Prakash Aishwarya
Publication year - 2019
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.23708
Subject(s) - pms2 , biology , msh2 , msh6 , genetics , missense mutation , nonsynonymous substitution , lynch syndrome , gene , dna mismatch repair , mutation , dna repair , genome
Abstract Lynch syndrome (LS) is an autosomal dominant inherited disorder that is associated with an increased predisposition to certain cancers caused by loss‐of‐function mutations in one of four DNA mismatch repair (MMR) genes ( MLH1 , MSH2 , MSH6 , or PMS2 ). The diagnosis of LS is often challenged by the identification of missense mutations where the functional effects are not known. These are termed variants of uncertain significance (VUSs) and account for 20%–30% of noncoding and missense mutations. VUSs cause ambiguity during clinical diagnosis and hinder implementation of appropriate medical management. In the current study, we focus on the functional and biological consequences of two nonsynonymous VUSs in PMS2 . These variants, c.620G>A and c.123_131delGTTAGTAGA, result in the alteration of glycine 207 to glutamate (p.Gly207Glu) and the deletion of amino acid residues 42–44 (p.Leu42_Glu44del), respectively. While the PMS2 p.Gly207Glu variant retains in vitro MMR and ATPase activities, PMS2 p.Leu42_Glu44del appears to lack such capabilities. Structural and biophysical characterization using circular dichroism, small‐angle X‐ray scattering, and X‐ray crystallography of the N‐terminal domain of the PMS2 variants indicate that the p.Gly207Glu variant is properly folded similar to the wild‐type enzyme, whereas p.Leu42_Glu44del is disordered and prone to aggregation.