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A novel homodimeric geranyl diphosphate synthase from the orchidPhalaenopsis bellinalacking a DD(X)2-4D motif
- Source :
- The Plant Journal. 55:719-733
- Publication Year :
- 2008
- Publisher :
- Wiley, 2008.
-
Abstract
- *† Contributed equally to this work. Summary Geranyl diphosphate (GDP) is the precursor of monoterpenes, which are the major floral scent compounds in Phalaenopsis bellina. The cDNA of P. bellina GDP synthase (PbGDPS) was cloned, and its sequence corresponds to the second Asp-rich motif (SARM), but not to any aspartate-rich (Asp-rich) motif. The recombinant PbGDPS enzyme exhibits dual prenyltransferase activity, producing both GDP and farnesyl diphosphate (FDP), and a yeast two-hybrid assay and gel filtration revealed that PbGDPS was able to form a homodimer. Spatial and temporal expression analyses showed that the expression of PbGDPS was flower specific, and that maximal PbGDPS expression was concomitant with maximal emission of monoterpenes on day 5 post-anthesis. Homology modelling of PbGDPS indicated that the Glu-rich motif might provide a binding site for Mg 2+ and catalyze the formation of prenyl products in a similar way to SARM. Replacement of the key Glu residues with alanine totally abolished enzyme activity, whereas their mutation to Asp resulted in a mutant with two-thirds of the activity of the wild-type protein. Phylogenetic analysis indicated that plant GDPS proteins formed four clades: members of both GDPS-a and GDPS-b clades contain Asp-rich motifs, and function as homodimers. In contrast, proteins in the GDPS-c and GDPS-d clades do not contain Asp-rich motifs, but although members of the GDPS-c clade function as heterodimers, PbGDPS, which is more closely related to the GDPS-c clade proteins than to GDPS-a and GDPS-b proteins, and is currently the sole member of the GDPS-d clade, functions as a homodimer.
- Subjects :
- Models, Molecular
DNA, Complementary
DNA, Plant
Molecular Sequence Data
Prenyltransferase
Mutant
Gene Expression
Prenyltransferase activity
Flowers
Plant Science
Genes, Plant
Complementary DNA
Genetics
Amino Acid Sequence
Cloning, Molecular
Binding site
Orchidaceae
Phylogeny
Plant Proteins
Alanine
Sequence Homology, Amino Acid
biology
ATP synthase
Reverse Transcriptase Polymerase Chain Reaction
Cell Biology
Dimethylallyltranstransferase
biology.organism_classification
Recombinant Proteins
Phalaenopsis bellina
Biochemistry
RNA, Plant
Odorants
Monoterpenes
Mutagenesis, Site-Directed
biology.protein
Sequence Alignment
Subjects
Details
- ISSN :
- 1365313X and 09607412
- Volume :
- 55
- Database :
- OpenAIRE
- Journal :
- The Plant Journal
- Accession number :
- edsair.doi.dedup.....bb6c0b1a807f9b5a33b6ceaae2845681