Adenine removal activity and bacterial complementation with the human MutY homologue (MUTYH) and Y165C, G382D, P391L and Q324R variants associated with colorectal cancer

摘要: MUTYH-associated polyposis (MAP) is the only inherited colorectal cancer syndrome that associated with biallelic mutations in a base excision repair gene. The MUTYH glycosylase plays an important role preventing 8-oxoguanine (OG) by removing adenine residues have been misincorporated opposite OG. MAP-associated are present throughout MUTYH, large number coding for missense variations. To date available information on functional properties of variants conflicting. In this study, kinetic analysis activity and several was undertaken using correction active fraction to control differences due overexpression purification. Using these methods, rate constants steps involved removal process were determined MAP Y165C, G382D, P391L Q324R MUTYH. Under single-turnover conditions, four found be 30-40% WT addition, ability suppress complement absence MutY Escherichia coli assessed rifampicin resistance assays. presence resulted complete suppression mutation frequency, while G382D showed reduced frequency. contrast, frequency observed upon expression Y165C similar controls, suggesting no toward DNA mutations. Notably, though all variations studied herein reductions activity, effects bacterial complementation quite different. This suggests consequences specific amino acid variation overall cellular context may magnified.