Cloning and characterization of a gene (UVR3) required for photorepair of 6-4 photoproducts in Arabidopsis thaliana.

摘要

UV radiation induces 2 major classes of pyrimidine dimers: the pyrimidine (6-4) pyrimidone photoproduct (6-4 product) and cyclobutane pyrimidine dimer (CPD). Many organisms produce photolyases that specifically bind to either CPDs or 6-4 damage products and split them via a UV-A/blue light-dependent mechanism. A gene (UVR3) that expresses a protein with 6-4 photolyase activity in vitro was isolated from A. thaliana. UVR3 produces a protein with 6-4 photolyase activity when expressed in Escherichiacoli. A previously described A. thaliana mutant (uvr3) that is defective in photoreactivation of 6-4 products carries a nonsense mutation in this 6-4 photolyase. Although homologues of this gene have previously been shown to produce a functional 6-4 photolyase when expressed in heterologous systems, this is the first demonstration of a requirement for this gene in the photoreactivation of 6-4 products in vivo.