Abstract
Cyclobutane pyrimidine dimer (CPD) is a major type of UV-induced DNA damage. CPD photolyase is a crucial factor for determining the sensitivity of plant to UVB. We previously reported that the native rice CPD photolyase, which was purified from rice leaves, was phosphorylated, whereas the E. coli-expressed rice CPD photolyase was not (Teranishi et al. Plant Physiol. 2008). Furthermore, the purified native rice CPD photolyase had significantly higher CPD photorepair activity than the E. coli-expressed CPD photolyase. These results suggested that the phosphorylation might affect the CPD photolyase activity. However, the purified native rice CPD photolyase possesses both pterin-like and FAD chromophores, whereas the E. coli-expressed rice CPD photolyase does not have the pterin-like chromophore. Thus, this result raises another possibility that the difference in the activity between the native rice CPD photolyase and E. coli-expressed rice CPD photolyase might be affected by the difference in the chromophore. To investigate the effect of phosphorylation on CPD photolyase activity, we separated phosphorylated and unphosphorylated CPD photolyase from the native rice CPD photolyase, and then we measured the activity of each CPD photolyase. As a result, there was no difference in the activity between phosphorylated and unphosphorylated CPD photolyase.
