Analysis of the Molecular Evolutionary History of the Ascorbate Peroxidase Gene Family: Inferences from the Rice Genome

0301 basic medicine Likelihood Functions Models, Genetic Molecular Sequence Data Computational Biology Oryza Evolution, Molecular Isoenzymes 03 medical and health sciences Ascorbate Peroxidases Peroxidases Gene Duplication Multigene Family Cluster Analysis Amino Acid Sequence Databases, Nucleic Acid Sequence Alignment Genome, Plant Phylogeny
DOI: 10.1007/s00239-004-2666-z Publication Date: 2004-12-13T10:32:40Z
ABSTRACT
Ascorbate peroxidase (APx) is a class I peroxidase that catalyzes the conversion of H(2)O(2) to H(2)O and O(2) using ascorbate as the specific electron donor. This enzyme has a key function in scavenging reactive oxygen species (ROS) and the protection against toxic effects of ROS in higher plants, algae, and Euglena. Here we report the identification of an APx multigene family in rice and propose a molecular evolutionary relationship between the diverse APx isoforms. In rice, the APx gene family has eight members, which encode two cytosolic, two putative peroxisomal, and four chloroplastic isoforms, respectively. Phylogenetic analyses were conducted using all APx protein sequences available in the NCBI databases. The results indicate that the different APx isoforms arose by a complex evolutionary process involving several gene duplications. The structural organization of APx genes also reflects this process and provides evidence for a close relationship among proteins located in the same subcellular compartment. A molecular evolutionary pathway, in which cytosolic and peroxisomal isoforms diverged early from chloroplastic ones, is proposed.
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