A single gene encodes isopentenyl diphosphate isomerase isoforms targeted to plastids, mitochondria and peroxisomes in Catharanthus roseus.
Isopentenyl diphosphate isomerases (IDI) catalyze the interconversion of the two isoprenoid universal C5 units, isopentenyl diphosphate and dimethylally diphosphate, to allow the biosynthesis of the large variety of isoprenoids including both primary and specialized metabolites. This isomerisation is usually performed by two distinct IDI isoforms located either in plastids/peroxisomes or mitochondria/peroxisomes as recently established in Arabidopsis thaliana mainly accumulating primary isoprenoids. By contrast, almost nothing is known in plants accumulating specialized isoprenoids. Here we report the cloning and functional validation of an IDI encoding cDNA (CrIDI1) from Catharanthus roseus that produces high amount of monoterpenoid indole alkaloids. The corresponding gene is expressed in all organs including roots, flowers and young leaves where transcripts have been detected in internal phloem parenchyma and epidermis. The CrIDI1 gene also produces long and short transcripts giving rise to corresponding proteins with and without a N-terminal transit peptide (TP), respectively. Expression of green fluorescent protein fusions revealed that the long isoform is targeted to both plastids and mitochondria with an apparent similar efficiency. Deletion/fusion experiments established that the first 18-residues of the N-terminal TP are solely responsible of the mitochondria targeting while the entire 77-residue long TP is needed for an additional plastid localization. The short isoform is targeted to peroxisomes in agreement with the presence of peroxisome targeting sequence at its C-terminal end. This complex plastid/mitochondria/peroxisomes triple targeting occurring in C. roseus producing specialized isoprenoid secondary metabolites is somehow different from the situation observed in A. thaliana mainly producing housekeeping isoprenoid metabolites.
EA2106 "Biomolécules et Biotechnologies Végétales", Université François Rabelais de Tours, 37200, Tours, France.
Grégory
G
Guirimand
Anthony
A
Guihur
Michael A
MA
Phillips
Audrey
A
Oudin
Gaëlle
G
Glévarec
Céline
C
Melin
Nicolas
N
Papon
Marc
M
Clastre
Benoit
B
St-Pierre
Manuel
M
Rodríguez-Concepción
Vincent
V
Burlat
Vincent
V
Courdavault
D000595:Amino Acid Sequence; D001483:Base Sequence; D019748:Carbon-Carbon Double Bond Isomerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030008:Catharanthus / Q000201:enzymology* / Q000235:genetics*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D045782:Hemiterpenes; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D020675:Peroxisomes / Q000201:enzymology; D030821:Plants, Genetically Modified; D018087:Plastids / Q000201:enzymology; D054730:Protein Interaction Domains and Motifs; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013729:Terpenes / Q000378:metabolism; D014170:Transformation, Genetic
D018744:DNA, Plant; D045782:Hemiterpenes; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D013729:Terpenes; D019748:Carbon-Carbon Double Bond Isomerases; C021453:isopentenyldiphosphate delta-isomerase