title: Culture temperature affects gene expression and metabolic pathways in the 2-methylisoborneol-producing cyanobacterium Pseudanabaena galeata.
abstract: A volatile metabolite, 2-methylisoborneol (2-MIB), causes an unpleasant taste and odor in tap water. Some filamentous cyanobacteria produce 2-MIB via a two-step biosynthetic pathway: methylation of geranyl diphosphate (GPP) by methyl transferase (GPPMT), followed by the cyclization of methyl-GPP by monoterpene cyclase (MIBS). We isolated the genes encoding GPPMT and MIBS from Pseudanabaena galeata, a filamentous cyanobacterium known to be a major causal organism of 2-MIB production in Japanese lakes. The predicted amino acid sequence showed high similarity with that of Pseudanabaena limnetica (96% identity in GPPMT and 97% identity in MIBS). P. galeata was cultured at different temperatures to examine the effect of growth conditions on the production of 2-MIB and major metabolites. Gas chromatograph-mass spectrometry (GC-MS) measurements showed higher accumulation of 2-MIB at 30 °C than at 4 °C or 20 °C after 24 h of culture. Real-time-RT PCR analysis showed that the expression levels of the genes encoding GPPMT and MIBS decreased at 4 °C and increased at 30 °C, compared with at 20 °C. Furthermore, metabolite analysis showed dramatic changes in primary metabolite concentrations in cyanobacteria grown at different temperatures. The data indicate that changes in carbon flow in the TCA cycle affect 2-MIB biosynthesis at higher temperatures.
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Saitama City Institute of Health Science and Research, 7-5-12 Suzuya, Chuo-ku, Saitama City, Saitama 338-0013, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kakimoto
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Miyagi
authors.affiliation: Saitama City Institute of Health Science and Research, 7-5-12 Suzuya, Chuo-ku, Saitama City, Saitama 338-0013, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Saito
authors.affiliation: Saitama City Institute of Health Science and Research, 7-5-12 Suzuya, Chuo-ku, Saitama City, Saitama 338-0013, Japan.
authors.forename: Motonobu
authors.initials: M
authors.lastname: Miyazaki
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Asaeda
authors.affiliation: Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan; Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan. Electronic address: mkawai@mail.saitama-u.ac.jp.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
mesh_terms: D001892:Camphanes / Q000378:metabolism; D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D053858:Metabolic Networks and Pathways / Q000502:physiology*; D013696:Temperature
chemical_list: D001892:Camphanes; C005536:2-methylisoborneol
keywords: 2-MIB; Cyanobacteria; Gene expression; Metabolomics; Temperature-induction