N. Cunillera et al., ARABIDOPSIS-THALIANA CONTAINS 2 DIFFERENTIALLY EXPRESSED FARNESYL-DIPHOSPHATE SYNTHASE GENES, The Journal of biological chemistry, 271(13), 1996, pp. 7774-7780
The enzyme farnesyl-diphosphate synthase (FPS; EC 2.5.1.1/EC 2.5.1.10)
catalyzes the synthesis of farnesyl diphosphate (FPP) from isopenteny
l diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). This reacti
on is considered to be a rate-limiting step in isoprenoid biosynthesis
. Southern blot analysis indicates that Arabidopsis thaliana contains
at least 2 genes (FPS1 and FPS2) encoding FPS. The FPS1 and FPS2 genes
have been cloned and characterized. The two genes have a very similar
organization with regard to intron positions and exon sizes and share
a high level of sequence similarity, not only in the coding region bu
t also in the intronic sequences. Northern blot analysis showed that F
PS1 and FPS2 have a different pattern of expression. FPS1 mRNA accumul
ates preferentially in roots and inflorescences, whereas FPS2 mRNA is
predominantly expressed in inflorescences. The cDNA corresponding to t
he FPS1 gene was isolated by functional complementation of a mutant ye
ast strain deffective in FPS activity (Delourme, D., Lacroute, F., and
Karst, F. (1994) Plant Mol. Biol. 26, 1867-1873). By using a reverse
transcription-polymerase chain reaction strategy we have cloned the cD
NA corresponding to the FPS2 gene. Analysis of the FPS2 cDNA sequence
revealed an open reading frame encoding a protein of 342 amino acid re
sidues with a predicted molecular mass of 39,825 Da. FPS1 and FPS2 iso
forms share an overall amino acid identity of 90.6%. Arabidopsis FPS2
was able to rescue the lethal phenotype of an ERG20-disrupted yeast st
rain. We demonstrate that FPS2 catalyzes the two successive condensati
ons of IPP with both DMAPP and geranyl diphosphate leading to FPP. The
significance of the occurrence of different FPS isoforms in plants is
discussed in the context of the complex organization of the plant iso
prenoid pathway.