title: A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L.
abstract: The green microalga Botryococcus braunii is considered a promising biofuel feedstock producer due to its prodigious accumulation of hydrocarbon oils that can be converted into fuels. B. braunii Race L produces the C40 tetraterpenoid hydrocarbon lycopadiene via an uncharacterized biosynthetic pathway. Structural similarities suggest this pathway follows a biosynthetic mechanism analogous to that of C30 squalene. Confirming this hypothesis, the current study identifies C20 geranylgeranyl diphosphate (GGPP) as a precursor for lycopaoctaene biosynthesis, the first committed intermediate in the production of lycopadiene. Two squalene synthase (SS)-like complementary DNAs are identified in race L with one encoding a true SS and the other encoding an enzyme with lycopaoctaene synthase (LOS) activity. Interestingly, LOS uses alternative C15 and C20 prenyl diphosphate substrates to produce combinatorial hybrid hydrocarbons, but almost exclusively uses GGPP in vivo. This discovery highlights how SS enzyme diversification results in the production of specialized tetraterpenoid oils in race L of B. braunii.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Hem R
authors.initials: HR
authors.lastname: Thapa
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.|Biomolecular NMR Laboratory, Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Mandar T
authors.initials: MT
authors.lastname: Naik
authors.affiliation: Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.|Japan Science and Technology Agency-Core Research for Evolutional Science and Technology (CREST), Gobancho, Chiyoda, Tokyo 102-0076, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Okada
authors.affiliation: Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.|Japan Science and Technology Agency-Core Research for Evolutional Science and Technology (CREST), Gobancho, Chiyoda, Tokyo 102-0076, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Takada
authors.affiliation: Natural Products Center, School of Natural Resources and the Environment, The University of Arizona, Tucson, Arizona 85739, USA.
authors.forename: István
authors.initials: I
authors.lastname: Molnár
authors.affiliation: Natural Products Center, School of Natural Resources and the Environment, The University of Arizona, Tucson, Arizona 85739, USA.|Biotechnology Research Institute, The Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Devarenne
mesh_terms: D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D000460:Chlorophyta / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D057075:Enzyme Assays; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D013186:Farnesyl-Diphosphate Farnesyltransferase / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013185:Squalene / Q000031:analogs & derivatives* / Q000378:metabolism; D013379:Substrate Specificity; D013729:Terpenes / Q000378:metabolism*; D014316:Tritium / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D018076:DNA, Complementary; D007527:Isoenzymes; D011106:Polyisoprenyl Phosphates; D011994:Recombinant Proteins; D013729:Terpenes; D014316:Tritium; D013185:Squalene; D013186:Farnesyl-Diphosphate Farnesyltransferase; C002963:geranylgeranyl pyrophosphate