Molecular cloning, characterization, genomic structure and functional analysis of catalase in Chilo suppressalis

Catalase (CAT), one of the key enzymes involved in protecting organisms from reactive oxygen species (ROS), degrades hydrogen peroxide to oxygen and water. In this study, we isolated the catalase gene (CsCAT) from the striped stern borer, Chilo suppressalis, a serious pest of rice in Asia. Sequence analysis of the genomic DNA indicated that CsCAT contains a 1023 bp intron and a 1524 bp coding sequence. The predicted CsCAT protein contains 507 amino acids and includes the proximal active site (FXRERIPERWHAKGXGA) and heme-ligand sequence (RLFSYNDTX) that are conserved in catalase enzymes. Phylogenetic analysis indicated that CAT from Lepidopteran moths could be assigned to one well-supported cluster. qRT-PCR indicated that CsCAT was expressed in insect heads, epidermis, fat body, foregut, midgut, hindgut, Malpighian tubules, and hemocytes. Expression of CsCAT was highest in the fat body and hemocytes of diapausing larvae, which suggests a potential important role in insect physiology during diapause period. Expression of CsCAT (measured by qRT-PCR) and enzymatic activity of CsCAT were not significantly altered by temperature stress, which indicates that CsCAT may insensitive to temperature. (C) 2016 Published by Elsevier B.V. on behalf of Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.