Ascorbate peroxidase-related (APx-R) is a new heme-containing protein functionally associated with ascorbate peroxidase but evolutionarily divergent

• Published in: The New phytologist 2011-07, Vol.191 (1), p.234-250
• Main Authors: Lazzarotto, Fernanda, Teixeira, Felipe Karam, Rosa, Silvia Barcelos, Dunand, Christophe, Fernandes, Claudia Lemelle, de Vasconcelos Fontenele, Adilton, Silveira, Joaquim Albenisio Gomes, Verli, Hugo, Margis, Rogério, Margis-Pinheiro, Marcia
• Format: Article
• Language: English
• Subjects: Aluminium; Aluminum; Amino Acid Sequence; antioxidant; Antioxidants; Antioxidants - metabolism; Arabidopsis - genetics; ascorbate peroxidase; Ascorbate Peroxidases; Ascorbic acid; Catalytic Domain; Chloroplasts; Chloroplasts - enzymology; Chromosomes; cold; Conserved Sequence; Dimerization; Divergence; Drought; Environmental stress; Evolution, Molecular; Gene families; Genes; Genetic loci; Genomics; H2O2 scavenging; Heme; heme peroxidase; Irradiation; L-Ascorbate peroxidase; Mitochondria - enzymology; Molecular Sequence Data; New class; New classes; Oryza - enzymology; Oryza - genetics; Oryza - growth & development; Oryza sativa; Peroxidase; Peroxidases - chemistry; Peroxidases - genetics; Peroxidases - physiology; Phylogenetics; Phylogeny; Plant interaction; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - physiology; Plants; Populus - genetics; Protein isoforms; Proteins; redox; Rice; RNA, Messenger - metabolism; Sequence Alignment; single copy gene; stress response; Stress, Physiological; Ultraviolet radiation
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2011.03659.x

• Peroxidases are involved in several important processes, such as development and responses to environmental cues. In higher plants, most peroxidases are encoded by large, multigenic families that mainly originated from gene and chromosomal duplications. • Using phylogenetic, genomic and functional analyses, we have identified and characterized a new class of putative heme peroxidases, called ascorbate peroxidase-related (APx-R), which arose specifically in the lineage of plants. • The APx-R protein is structurally related to the ascorbate peroxidases, although the active site contains many conserved substitutions. Unlike all other plant peroxidases, which are encoded by gene families, APx-R is encoded by a single-copy gene in virtually all the species analyzed. APx-R proteins are targeted to the chloroplast and can physically interact with chloroplastic APx proteins. APx-R-knockdown rice (Oryza sativa) plants presented delayed development and a disturbed steady state of the antioxidant system compared with wild type. Moreover, the accumulation of APx-R transcripts was modulated by drought, UV irradiation, cold, and aluminum exposure in rice, suggesting the involvement of APx-R in the environmental stress response. • Our results reveal the existence of a new class of heme peroxidase which seems to play a role in the antioxidant system in plants, probably by modulating the activity of chloroplastic APx proteins.