Pathway-Level Acceleration of Glycogen Catabolism by a Response Regulator in the Cyanobacterium Synechocystis Species PCC 6803  

Abstract

Response regulators of two-component systems play pivotal roles in the transcriptional regulation of responses to environmental signals in bacteria. Rre37, an OmpR-type response regulator, is induced by nitrogen depletion in the unicellular cyanobacterium Synechocystis species PCC 6803. Microarray and quantitative real-time polymerase chain reaction analyses revealed that genes related to sugar catabolism and nitrogen metabolism were up-regulated by rre37 overexpression. Protein levels of GlgP(slr1367), one of the two glycogen phosphorylases, in the rre37-overexpressing strain were higher than those of the parental wild-type strain under both nitrogen-replete and nitrogen-depleted conditions. Glycogen amounts decreased to less than one-tenth by rre37 overexpression under nitrogen-replete conditions. Metabolome analysis revealed that metabolites of the sugar catabolic pathway and amino acids were altered in the rre37-overexpressing strain after nitrogen depletion. These results demonstrate that Rre37 is a pathway-level regulator that activates the metabolic flow from glycogen to polyhydroxybutyrate and the hybrid tricarboxylic acid and ornithine cycle, unraveling the mechanism of the transcriptional regulation of primary metabolism in this unicellular cyanobacterium.

Sucrose Synthesis in the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC 7120 Is Controlled by the Two-Component Response Regulator OrrA

“…Thus, OrrA plays a pivotal role in the regulation of sucrose synthesis. Metabolic engineering using a transcriptional regulator that regulates sugar catabolism has succeeded in accelerating production of bioplastics in Synechocystis PCC 6803 (39,40). OrrA should be applicable to metabolic engineering of sucrose production by cyanobacteria.…”

Two-stage (photoautotrophy and heterotrophy) cultivation enables efficient production of bioplastic poly-3-hydroxybutyrate in auto-sedimenting cyanobacterium

“…In the cyanobacterium Synechocystis sp. PCC6803, where the PHB synthesis pathway has been completely identified, culturing in -N or -P medium was found to enhance the photoautotrophic PHB accumulation by increasing the activity levels of the three enzymes in the PHB synthetic pathway222324.…”

Poly(amino acid)s/polypeptides as potential functional and structural materials

“…75 Contrary to amyloid fibrils, silk β-sheets composed of Gly and Ala did not express significant cytotoxicity, most likely because of a lack of electrical charge. Nano-assembly of silk β-sheets produced microfibrils after incubation for 72 h (Figure 5a), and formation of the nano-assembly was faster than that of Aβ (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), Aβ (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42) and full-length Aβ(1-42) because of the greater hydrophobicity of the silk β-sheet. 76,77 The control of silk β-sheet formation is key the assembly needed to create artificial tough polymeric materials; however, this control has not yet been established because β-sheets assemble via hydrophobic interactions too quickly to regulate in solution.…”

“…[4][5][6][7][8][9][10][11][12] Poly(hydroxyalkanoate) has several advantages such as the ability to be directly synthesized from various types of biomass, including lignin and carbon dioxide, [13][14][15][16][17] and excellent biodegradability. 18,19 However, because of a lack of toughness, this biopolyester has limited use and application.…”