Isolation and characterization of a novel PHGPx gene in Raphanus sativus

A full-length cDNA encoding putative phospholipid hydroperoxide glutathione peroxidase (PHGPx) was cloned from Raphanus sativus. The cDNA, designated RsPHGPx, includes an open reading frame which encodes 197 amino acid residues. The alignment of amino acid sequences showed that RsPHGPx had the highest sequence homology to plant PHGPx and contained an N-terminal extension characteristic of a mitochondrial targeting peptide. Northern blot analysis indicated that RsPHGPx was constitutively and ubiquitously expressed during radish development, and its expression was differently regulated by various stress conditions. The expression of RsPHGPx in a yeast PHGPx-deletion mutant significantly rescued the mutant sensitivity to oxidation-sensitive linolenic acid, just as the yeast PHGPx3 gene did. This suggested that RsPHGPx encodes a functional PHGPx protein.