Molecular identification and properties of a light-insensitive rice catalase-B expressed in E. coli

Catalase plays a central role in plant stress responses but is highly susceptible to photoinhibition. A rice catalase-B protein avoiding photoinhibition was developed by mutagenesis of specific amino acids: Leu-189 to Trp-189 and His-225 to Thr-225 and then recombinantly expressed in E. coli. In addition, the site specific mutation also induced 2-2.5-fold increase in enzyme velocity with high affinity for its substrate and showed nearly a 3-fold lower K(m) than the wild protein. These characteristic of mutated rice catalase-B is highly promising in transgenic research to increase plant productivity under stress conditions.