PMID:16150417

Citation	Iijima, Y, Wang, G, Fridman, E and Pichersky, E (2006) Analysis of the enzymatic formation of citral in the glands of sweet basil. Arch. Biochem. Biophys. 448:141-9
Abstract	Basil glands of the Sweet Dani cultivar contain high levels of citral, a mixture of geranial and its cis-isomer neral, as well as low levels of geraniol and nerol. We have previously reported the identification of a cDNA from Sweet Dani that encodes an enzyme responsible for the formation of geraniol from geranyl diphosphate in the glands, and that these glands cannot synthesize nerol directly from geranyl diphosphate. Here, we report the identification of two basil cDNAs encoding NADP+-dependent dehydrogenases that can use geraniol as the substrate. One cDNA, designated CAD1, represents a gene whose expression is highly specific to gland cells of all three basil cultivars examined, regardless of their citral content, and encodes an enzyme with high sequence similarity to known cinnamyl alcohol dehydrogenases (CADs). The enzyme encoded by CAD1 reversibly oxidizes geraniol to produce geranial (which reversibly isomerizes to neral via keto-enol tautomerization) at half the efficiency compared with its activity with cinnamyl alcohol. CAD1 does not use nerol and neral as substrates. A second cDNA, designated GEDH1, encodes an enzyme with sequence similarity to CAD1 that is capable of reversibly oxidizing geraniol and nerol in equal efficiency, and prolonged incubation of geraniol with GEDH1 in vitro produces not only geranial and neral, but also nerol. GEDH1 is also active, although at a lower efficiency, with cinnamyl alcohol. However, GEDH1 is expressed at low levels in glands of all cultivars compared with its expression in leaves. These and additional data presented indicate that basil glands may contain additional dehydrogenases capable of oxidizing geraniol.
Links	PubMed Online version:10.1016/j.abb.2005.07.026
Keywords	Amino Acid Sequence; Enzyme Activation; Molecular Sequence Data; Monoterpenes/chemistry; Monoterpenes/metabolism; NADP/chemistry; NADP/genetics; NADP/metabolism; Ocimum basilicum/enzymology; Ocimum basilicum/genetics; Plant Structures/enzymology; Plant Structures/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
OCIBA:GEDH1	NOT	GO:0047924: geraniol dehydrogenase activity	ECO:0000314:		F		Fig. 5 shows geraniol oxidation by CAD1 or GEDH1 to produce geranial.	complete CACAO 4642

References

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