Abstract
Cyclobutane pyrimidine dimer (CPD) photolyase is a crucial factor for determining UVB sensitivity in plant. This enzyme binds specifically to CPDs in DNA. By absorbing blue/UVA radiation, the dimer is reversed to monomer pyrimidines and the enzyme is released. Rice CPD photolyase overexpressed in E.coli is known to be a single ca. 55-kDa protein. Up-to-date native class II CPD photolyase has been studied yet. Recently we generated highly UV-resistant Sasanishiki plant bearing the CPD photolyase gene of Sasanishiki in the sense orientation. The content of CPD photolyase in this transgenic plant is extremely higher than that in wild plant. We purified sequentially CPD photolyase from the transgenic plant with several steps of column- and affinity-chromatographies and investigated the nature of the purified enzyme. This paper shows that isoforms of CPD photolyase of two 54- and 56-kDa proteins are involved in rice.
