Open AccessMutations in human AID differentially affect its ability to deaminate cytidine and 5-methylcytidine in ssDNA substrates in vitro
Author(s) -
Lucyna Budzko,
Paulina Jackowiak,
Karol Kamel,
Joanna Sarzyńska,
Janusz Bujnicki,
Marek Figlerowicz
Publication year - 2017
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/s41598-017-03936-x
Subject(s) - deamination , cytidine deaminase , cytidine , activation induced (cytidine) deaminase , dna demethylation , in vitro , biochemistry , enzyme , biology , apobec3g , mutant , dna , chemistry , genetics , gene , antibody , somatic hypermutation , dna methylation , gene expression , b cell
Activation-induced cytidine deaminase (AID) is known for its established role in antibody production. AID induces the diversification of antibodies by deaminating deoxycytidine (C) within immunoglobulin genes. The capacity of AID to deaminate 5-methyldeoxycytidine (5 mC) and/or 5-hydroxymethyldeoxycytidine (5 hmC), and consequently AID involvement in active DNA demethylation, is not fully resolved. For instance, structural determinants of AID activity on different substrates remain to be identified. To better understand the latter issue, we tested how mutations in human AID (hAID) influence its ability to deaminate C, 5 mC, and 5 hmC in vitro . We showed that each of the selected mutations differentially affects hAID’s ability to deaminate C and 5 mC. At the same time, we did not observe hAID activity on 5 hmC. Surprisingly, we found that the N51A hAID mutant, with no detectable activity on C, efficiently deaminated 5 mC, which may suggest different requirements for C and 5 mC deamination. Homology modeling and molecular dynamics simulations revealed that the pattern of enzyme-substrate recognition is one of the important factors determining enzyme activity on C and 5 mC. Consequently, we have proposed mechanisms that explain why wild type hAID more efficiently deaminates C than 5 mC in vitro and why 5 hmC is not deaminated.