Geraniol, a naturally occurring straight chain terpene alcohol, is structurally related to citronellol and differs only by the presence of an additional double bond (Cantwell et al., 1978). Geraniol is produced by many flowering plants, including geraniums and citrus fruits, and in the scent glands of honey bees. It is used commercially for its flavor and fragrance (Hoschle et al., 2005). No toxicity was found in geraniol.
The first steps of geraniol degradation in Pseudomonas aeruginosa, Pseudomonas citronellolis and Pseudomonas mendocina involve the oxidation of the alcohol to the corresponding aldehyde and acid (geranial and geranylate) and subsequent activation to the corresponding CoA ester geranyl-CoA (Hoschle et al., 2005). The citronellol and geraniol pathways converge at this point and the beta-methyl group inhibiting beta-oxidation is converted to an acetate by geranyl-CoA carboxylase. Two rounds of beta-oxidation follows the hydratization and elimination of the acetate side group to produce 3-methylcrotonyl-CoA (Hoschle et al., 2005).
The following is a text-format geraniol degradation pathway map. Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (5k) format.
Geraniol Pseudomonas aeruginosa Pseudomonas citronellolis Pseudomonas mendocina | | | geraniol | dehydrogenase | | v Geranial | | | geranial | dehydrogenase | | v Geranylate | | | geranylate | CoA-transferase | | v trans-Geranyl-CoA | | | trans-geranyl-CoA | isomerase | | v cis-Geranyl-CoA | | | | | v to the Citronellol Pathway
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