02732nas a2200325   4500008004100000245008100041210006900122260000800191300001200199490000800211520172200219653003201941653002401973653002301997653001502020653002002035653001702055653002802072653002102100653001402121653002102135653003402156653001302190100001702203700001902220700001802239700002202257700002002279856010702299       2004                        eng d00aCharacterization of geraniol synthase from the peltate glands of sweet basil0 aCharacterization of geraniol synthase from the peltate glands of  cJan  a370–90 v1343 aThe monoterpene fraction of the lemon-scented sweet basil (Ocimum basilicum) cv Sweet Dani consists mostly of citral (a mixture of geranial and neral), with lower levels of geraniol and nerol. These compounds are stored in the peltate glands found on the leaf epidermis. Younger leaves, which have a higher density of such glands, also have a higher content of monoterpenes than older leaves. Geraniol synthase (GES) activity, generating geraniol from geranyl diphosphate, was shown to be localized exclusively or almost exclusively to glands. GES activity resides in a homodimeric protein that was purified to near homogeneity. Basil GES requires Mn2+ as a divalent metal cofactor for activity and produces only geraniol from geranyl diphosphate. Km values of 21 and 51 microM were obtained for geranyl diphosphate and Mn2+, respectively. In the presence of 18O-labeled water, GES catalyzed the formation of 18O-geraniol from geranyl diphosphate, indicating that the reaction mechanism of GES is similar to that of other monoterpene synthases and is different from the action of phosphatases. A GES cDNA was isolated based on analysis of a glandular trichome expressed sequence tag database, and the sequence of the protein encoded by this cDNA shows some similarity to sequences of other terpene synthases. The expression of the GES cDNA in Escherichia coli resulted in a protein with enzymatic activity essentially identical to that of plant-purified GES. RNA gel-blot analysis indicated that GES is expressed in glands but not in leaves of basil cv Sweet Dani, whose glands contain geraniol and citral, and not in glands or leaves of another basil variety that makes other monoterpenes but not geraniol or citral.10aAlkyl and Aryl Transferases10aAmino Acid Sequence10aDNA: Complementary10aDNA: Plant10aGene Expression10aGenes: Plant10aMolecular Sequence Data10aOcimum basilicum10aPhylogeny10aPlant Structures10aSequence Homology: Amino Acid10aTerpenes1 aIijima, Yoko1 aGang, David, R1 aFridman, Eyal1 aLewinsohn, Efraim1 aPichersky, Eran  uhttps://lamiaceae.myspecies.info/content/characterization-geraniol-synthase-peltate-glands-sweet-basil