title: Genetic engineering of group 2 sigma factor SigE widely activates expressions of sugar catabolic genes in Synechocystis species PCC 6803.
abstract: Metabolic engineering of photosynthetic organisms is required for utilization of light energy and for reducing carbon emissions.Control of transcriptional regulators is a powerful approach for changing cellular dynamics, because a set of genes is concomitantly regulated. Here, we show that overexpression of a group 2 σ factor, SigE, enhances the expressions of sugar catabolic genes in the unicellular cyanobacterium, Synechocystis sp. PCC 6803. Transcriptome analysis revealed that genes for the oxidative pentose phosphate pathway and glycogen catabolism are induced by overproduction of SigE. Immunoblotting showed that protein levels of sugar catabolic enzymes, such as glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glycogen phosphorylase, and isoamylase, are increased. Glycogen levels are reduced in the SigE-overexpressing strain grown under light. Metabolome analysis revealed that metabolite levels of the TCA cycle and acetyl-CoA are significantly altered by SigE overexpression. The SigE-overexpressing strain also exhibited defective growth under mixotrophic or dark conditions. Thus, SigE overexpression changes sugar catabolism at the transcript to phenotype levels, suggesting a σ factor-based engineering method for modifying carbon metabolism in photosynthetic bacteria.
authors.affiliation: Department of Life Sciences (Biology), University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902; RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012. Electronic address: tosanai@psc.riken.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Osanai
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045.
authors.forename: Akira
authors.initials: A
authors.lastname: Oikawa
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Azuma
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032; Graduate School of Horticulture, Chiba University, 648 Matsudo, Chiba 271-8510.
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045; Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045.
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
authors.affiliation: Department of Life Sciences (Biology), University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002241:Carbohydrates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D000458:Cyanobacteria / Q000378:metabolism; D019075:Electrophoresis, Capillary; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering; D006003:Glycogen / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D008957:Models, Genetic; D045332:Photosystem II Protein Complex; D012808:Sigma Factor / Q000378:metabolism*; D015398:Signal Transduction; D046939:Synechocystis / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D045332:Photosystem II Protein Complex; D012808:Sigma Factor; C111259:sigE protein, Bacteria; D002244:Carbon; D006003:Glycogen