title: The Effects of Dark Incubation on Cellular Metabolism of the Wild Type Cyanobacterium Synechocystis sp. PCC 6803 and a Mutant Lacking the Transcriptional Regulator cyAbrB2.
abstract: The cyAbrB2 transcriptional regulator is essential for active sugar catabolism in Synechocystis sp. PCC 6803 grown under light conditions. In the light-grown cyabrB2-disrupted mutant, glycogen granules and sugar phosphates corresponding to early steps in the glycolytic pathway accumulated to higher levels than those in the wild-type (WT) strain, whereas the amounts of 3-phosphoglycerate, phosphoenolpyruvate and ribulose 1,5-bisphosphate were significantly lower. We further determined that accumulated glycogen granules in the mutant could be actively catabolized under dark conditions. Differences in metabolite levels between WT and the mutant became less substantial during dark incubation due to a general quantitative decrease in metabolite levels. Notable exceptions, however, were increases in 2-oxoglutarate, histidine, ornithine and citrulline in the WT but not in the mutant. The amounts of cyAbrBs were highly responsive to the availability of light both in transcript and protein levels. When grown under light-dark cycle conditions, diurnal oscillatory pattern of glycogen content of the mutant was lost after the second dark period. These observations indicate that cyAbrB2 is dispensable for activation of sugar catabolism under dark conditions but involved in the proper switching between day and night metabolisms.
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. s13mb111@mail.saitama-u.ac.jp.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Hanai
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. s14mb115@mail.saitama-u.ac.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. miyagi@mail.saitama-u.ac.jp.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Miyagi
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. mkawai@mail.saitama-u.ac.jp.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. kytanaka@mail.saitama-u.ac.jp.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. yakaneko@mail.saitama-u.ac.jp.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kaneko
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. nishiyama@molbiol.saitama-u.ac.jp.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nishiyama
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. hihara@molbiol.saitama-u.ac.jp.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Hihara