A Plastid Terminal Oxidase Associated with Carotenoid Desaturation during Chromoplast Differentiation

• Published in: Plant physiology (Bethesda) 2000-08, Vol.123 (4), p.1427-1436
• Main Authors: Josse, Eve-Marie, Andrew J. Simkin, Joël Gaffé, Anne-Marie Labouré, Kuntz, Marcel, Carol, Pierre
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; alternative oxidase; Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins; Arabidopsis thaliana; Base Sequence; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Blotting, Southern; Capsicum - genetics; Capsicum - metabolism; Capsicum annuum; Carotenoids; Carotenoids - biosynthesis; Carotenoids - metabolism; Chemical desaturation; Chloroplasts - metabolism; Chromoplasts; Complementary DNA; Economic plant physiology; Escherichia coli - genetics; Escherichia coli - metabolism; Fructification, ripening. Postharvest physiology; Fundamental and applied biological sciences. Psychology; Genomics; Growth and development; Immunoblotting; IMMUTANS gene; Lycopersicon esculentum - genetics; Lycopersicon esculentum - metabolism; Metabolism; Molecular Sequence Data; Mutation; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Oxidases; Peppers; phytoene desaturase; Plant physiology and development; Plants; Plants - genetics; Plants - metabolism; Plants, Medicinal; plastid terminal oxidase; Plastids; Plastids - metabolism; PTOX gene; Q-carotene desaturase; quinol:oxygen oxidoreductase; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger - analysis; Sequence Homology, Amino Acid; Storage and secretion, pigments, phytochrome
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.123.4.1427

The Arabidopsis IMMUTANS gene encodes a plastid homolog of the mitochondrial alternative oxidase, which is associated with phytoene desaturation. Upon expression in Escherichia coli, this protein confers a detectable cyanide-resistant electron transport to isolated membranes. In this assay this activity is sensitive to n-propyl-gallate, an inhibitor of the alternative oxidase. This protein appears to be a plastid terminal oxidase (PTOX) that is functionally equivalent to a quinol:oxygen oxidoreductase. This protein was immunodetected in achlorophyllous pepper (Capsicum annuum) chromoplast membranes, and a corresponding cDNA was cloned from pepper and tomato (Lycopersicum esculentum) fruits. Genomic analysis suggests the presence of a single gene in these organisms, the expression of which parallels phytoene desaturase and ζ-carotene desaturase gene expression during fruit ripening. Furthermore, this PTOX gene is impaired in the tomato ghost mutant, which accumulates phytoene in leaves and fruits. These data show that PTOX also participates in carotenoid desaturation in chromoplasts in addition to its role during early chloroplast development.