Co-expression of Two Polyhydroxyalkanoate Synthase Subunits from Synechocystis sp. PCC 6803 by Cell-Free Synthesis and Their Specific Activity for Polymerization of 3-Hydroxybutyryl-Coenzyme A

Abstract

Synechocystis sp. PCC 6803 is one of the most studied cyanobacteria for polyhydroxyalkanoate (PHA) synthesis, and its PHA synthase is known to consist of two subunits, namely, PhaC and PhaE. This report is the first to show the specific activity and related biochemical properties of PHA synthase from cyanobacteria. We have cloned and prepared a complex of PhaC and PhaE (PhaCE) from Synechocystis sp. PCC 6803 by the co-expression of PhaC and PhaE using a cell-free synthesis system. The specific activity of PhaCE was comparable to that of the class I PHA synthases, indicating that the low PHA productivity of cyanobacteria is not due to the activity of PHA synthase but may be caused by the other metabolic reactions related to PHA synthesis. The positive Hill coefficient of PhaCE as well as the size exclusion chromatography data indicates that dimeric PhaCE is a major active form that polymerizes 3-hydroxybutyryl-coenzyme A.

Identification of Four Polyhydroxyalkanoate Structural Genes in Synechocystis cf. salina PCC6909: In silico Evidences

“…Recently, the activity of the co-expressed PhaE and PhaC in a cell-free system was determined and the values obtained were comparable to those of PHA synthases belonging to class I [22]. The PhaE-C complex activity is essential for PHA polymerization but not crucial for the PHA yield, suggesting the involvement of significant regulative mechanisms combined to photosynthetic activity and glycogen biosynthesis [22][23][24]. Several attempts of genetic modification were performed mainly through the transfer of genes belonging to heterotrophic bacteria [25].…”

“…At this stage, a heterodimer complex composed of PhaE [poly (3-hydroxyalkanoate) synthase component] and PhaC [poly(3-hydroxyalkanoate) synthase] polymerizes the Hydroxybutyryl-CoA to Polyhydroxybutyrate [21]. Recently, the activity of the co-expressed PhaE and PhaC in a cell-free system was determined and the values obtained were comparable to those of PHA synthases belonging to class I [22]. The PhaE-C complex activity is essential for PHA polymerization but not crucial for the PHA yield, suggesting the involvement of significant regulative mechanisms combined to photosynthetic activity and glycogen biosynthesis [22][23][24].…”

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

“…[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.…”

“…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.…”

Experimental investigation of the fire extinguishing capability of ferrocene-containing water mist

“…2b-d. These surfactants are widely used in bio-, food, agricultural, and organic chemistry [17][18][19][20][21]; for instance, a feature of NT is its high biodegradability. Ferrocene and the four surfactants were used as received, without further purification.…”