title: Isolation and characterization of two squalene epoxidase genes from Botryococcus braunii, race B.
abstract: The B race of the green microalga Botryococcus braunii produces triterpene hydrocarbons, botryococcenes and methylsqualenes that can be processed into jet fuels with high heating values. In this alga, squalene is also converted into membrane sterols after 2,3-epoxidation. In the present study, cDNA clones of two distinct squalene epoxidases (BbSQE-I and -II) were isolated. Predicted amino acid sequences encoded on these genes are 45% identical with each other. Introduction of BbSQE-I or -II into Saccharomyces cerevisie erg1 mutants resulted in the complementation of ergosterol auxotrophy. The relative expression level of SQE-II increased 3.5-fold from the early stage to the middle phase of a culture period of 42 days, while that of SQE-I was almost constant throughout the culture period. Southern blot analyses suggested that these genes are single-copied genes. This is the first report on the isolation of functional SQEs that are encoded in duplicated loci in the algal genome.
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: Hidenobu
authors.initials: H
authors.lastname: Uchida
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: Koremitsu
authors.initials: K
authors.lastname: Sumimoto
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; Institute of Aquaculture, University of the Philippines Visayas, Miagao, 5023 Iloilo, Philippines.
authors.forename: Victor Marco Emmanuel
authors.initials: VM
authors.lastname: Ferriols
authors.affiliation: Laboratory of Biological and Mechanical Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Imou
authors.affiliation: Laboratory of Biological and Mechanical Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Saga
authors.affiliation: Laboratory of Biological and Mechanical Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Furuhashi
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: Shigeki
authors.initials: S
authors.lastname: Matsunaga
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
mesh_terms: D000595:Amino Acid Sequence; D000460:Chlorophyta / Q000201:enzymology / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D015870:Gene Expression; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D050603:Squalene Monooxygenase / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D050603:Squalene Monooxygenase
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