APE1 active site residue Asn174 stabilizes the AP site and is essential for catalysis.

ABSTRACT: Apurinic/apyrimidinic (AP) sites are common and highly mutagenic DNA lesions that can arise spontaneously or as intermediates during base excision repair. The enzyme apurinic/apyrimidinic endonuclease 1 (APE1) initiates repair of AP sites by cleaving the DNA backbone at the AP site via its endonuclease activity. Here, we investigated the functional role of the APE1 active site residue N174 that contacts the AP site during catalysis. To do so, we rationally designed four APE1 mutants (N174A, N174D, N174Q, and N174K) that altered the hydrogen bonding potential, electronegativity, and side chain length of residue 174. Kinetic analysis determined that AP site cleavage was impaired in our APE1_N174A, APE1_N174D, and APE1_N174K mutants, but not in our APE1_N174Q

SUBMITTER: DeHart KM 

PROVIDER: S-EPMC12557600 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature