A plastid terminal oxidase associated with carotenoid desaturation during chromoplast differentiation.
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 zeta-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.
Laboratoire de Génétique Moléculaire des Plantes, Université Joseph Fourier and Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5575), BP53, 38041 Grenoble cedex 9, France.
E M
EM
Josse
A J
AJ
Simkin
J
J
Gaffé
A M
AM
Labouré
M
M
Kuntz
P
P
Carol
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins; D001483:Base Sequence; D015139:Blotting, Southern; D002212:Capsicum / Q000235:genetics / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis* / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D010946:Plants, Medicinal; D018087:Plastids / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D002338:Carotenoids; D009687:Nuclear Proteins; D012333:RNA, Messenger; C405742:IM protein, Arabidopsis; C100185:(all-E) phytoene