Expanded Substrate Scope of DNA Polymerase θ and DNA Polymerase ß: Lyase Activity on 5'-Overhangs and Clustered Lesions.
Biochemistry
; 57(42): 6119-6127, 2018 10 23.
Article
en En
| MEDLINE
| ID: mdl-30299084
ABSTRACT
DNA polymerase θ (Pol θ) is a multifunctional enzyme with double-strand break (DSB) repair, translesion synthesis, and lyase activities. Pol θ lyase activity on ternary substrates containing a 5'-dRP that are produced during base excision repair of abasic sites (AP) is weak compared to that of DNA polymerase ß (Pol ß), a polymerase integrally involved in base excision repair. This led us to explore whether Pol θ utilizes its lyase activity to remove 5'-dRP and incise abasic sites from alternative substrates that might be produced during DNA damage and repair. We found that Pol θ exhibited lyase activity on abasic lesions near DSB termini and on clustered lesions. To calibrate the Pol θ activity, Pol ß reactivity was examined with the same substrates. Pol ß excised 5'-dRP from within a 5'-overhang 80 times faster than did Pol θ. Pol θ and Pol ß also incised AP within clustered lesions but showed opposite preferences with respect to the polarity of the lesions. AP lesions in 5'-overhangs were typically excised by Pol ß 35-50 times faster than those in a duplex substrate but 15-20-fold more slowly than 5'-dRP in a ternary complex. This is the first report of Pol θ exhibiting lyase activity within an unincised strand. These results suggest that bifunctional polymerases may exhibit lyase activity on a greater variety of substrates than previously recognized. A role in DSB repair could potentially be beneficial, while the aberrant activity exhibited on clustered lesions may be deleterious because of their conversion to DSBs.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Daño del ADN
/
Liasas de Fósforo-Oxígeno
/
ADN Polimerasa beta
/
ADN Polimerasa Dirigida por ADN
/
Reparación del ADN
/
Replicación del ADN
Límite:
Humans
Idioma:
En
Revista:
Biochemistry
Año:
2018
Tipo del documento:
Article
País de afiliación:
Estados Unidos