title: Evolution of the isoprene biosynthetic pathway in kudzu.
abstract: Isoprene synthase converts dimethylallyl diphosphate, derived from the methylerythritol 4-phosphate (MEP) pathway, to isoprene. Isoprene is made by some plants in substantial amounts, which affects atmospheric chemistry, while other plants make no isoprene. As part of our long-term study of isoprene synthesis, the genetics of the isoprene biosynthetic pathway of the isoprene emitter, kudzu (Pueraria montana), was compared with similar genes in Arabidopsis (Arabidopsis thaliana), which does not make isoprene. The MEP pathway genes in kudzu were similar to the corresponding Arabidopsis genes. Isoprene synthase genes of kudzu and aspen (Populus tremuloides) were cloned to compare their divergence with the divergence seen in MEP pathway genes. Phylogenetic analysis of the terpene synthase gene family indicated that isoprene synthases are either within the monoterpene synthase clade or sister to it. In Arabidopsis, the gene most similar to isoprene synthase is a myrcene/ocimene (acyclic monoterpenes) synthase. Two phenylalanine residues found exclusively in isoprene synthases make the active site smaller than other terpene synthase enzymes, possibly conferring specificity for the five-carbon substrate rather than precursors of the larger isoprenoids. Expression of the kudzu isoprene synthase gene in Arabidopsis caused Arabidopsis to emit isoprene, indicating that whether or not a plant emits isoprene depends on whether or not it has a terpene synthase capable of using dimethylallyl diphosphate.
authors.affiliation: Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, USA. tsharkey@wisc.edu
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Sharkey
authors.forename: Sansun
authors.initials: S
authors.lastname: Yeh
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wiberley
authors.forename: Tanya G
authors.initials: TG
authors.lastname: Falbel
authors.forename: Deming
authors.initials: D
authors.lastname: Gong
authors.forename: Donna E
authors.initials: DE
authors.lastname: Fernandez
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D001665:Binding Sites; D002070:Butadienes; D002874:Chromosome Mapping; D004896:Erythritol / Q000031:analogs & derivatives* / Q000378:metabolism; D019143:Evolution, Molecular; D045782:Hemiterpenes / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010420:Pentanes; D010641:Phenotype; D010802:Phylogeny; D032107:Populus / Q000201:enzymology; D029908:Pueraria / Q000201:enzymology* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013403:Sugar Phosphates / Q000378:metabolism
chemical_list: C114232:2-C-methylerythritol 4-phosphate; D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; D013403:Sugar Phosphates; C005059:isoprene; D019883:Alkyl and Aryl Transferases; C093854:isoprene synthase; D004896:Erythritol