The importance of PHB-synthase substrate specificity in polyhydroxyalkanoate synthesis by Alcaligenes eutrophus

Haywood, G

doi:10.1016/0378-1097(89)90519-3

Cited by 60 publications

(94 citation statements)

References 4 publications

(4 reference statements)

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“…PHB synthase of N. muscorum was exclusively detected in soluble fractions of control as well as the cultures incubated under chemoheterotrophic condition (Table 1). This agrees well with the reports of Fukui et al (1976), Haywood et al (1989) and Liebergesell et al (1994), where PHB synthase activity was detected in soluble fractions of Zoogloea ramigera, Chromatium vinosum, and Wautersia eutropha, respectively, but contradicts Miyake et al (1997) where PHB synthase of Synechococcus MA19 was a membrane-bound enzyme. The membrane-bound nature of Synechococcus PHB synthase resulted in formation of PHB granules very closely associated and surrounded with thylakoid membrane (Asada et al, 1999).…”

Section: Discussionsupporting

confidence: 92%

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Studies on poly-β-hydroxybutyrate synthase activity of Nostoc muscorum

Sharma

Panda

Singh

et al. 2006

J. Gen. Appl. Microbiol.

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IntroductionPoly-b-hydroxybutyrate (PHB) is a class of naturally occurring polyester which is produced and stored intracellularly in wide varieties of prokaryotes including cyanobacteria under unbalanced growth conditions (Anderson and Dawes, 1990;Stal, 1992;Steinbüchel, 1991). This polymer has attracted the researchers because of its potential to be an alternative to conventional plastics.The cyanobacterium, Nostoc muscorum accumulates PHB profoundly under conditions of nutrient (N and P) deprivation, mixotrophy, chemoheterotrophy and limitations of gas exchange. Our earlier reports (Sharma and Mallick, 2005a, b) demonstrated accumulation up to 23, 25, 35, 43 and 40% of dry cell weight (dcw), respectively under P-deficient, N-deficient, mixotrophic, chemoheterotrophic and gas exchange limited conditions, as compared to a PHB pool of 8.5% (dcw) in control culture. PHB metabolism has been studied in PHB-accumulating bacteria, especially in Alcaligenes eutrophus, now called Wautersia eutropha. PHB is synthesized from acetyl-CoA via three enzymatic reactions: 3-ketothiolase (EC 2.3.1.9) converts two acetyl-CoA molecules to an acetoacetyl-CoA molecule, NADPH-dependent acetoacetyl-CoA reductase (EC 1.1.

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Section: Discussionsupporting

confidence: 92%

“…2). This is much closer to the value reported for Synechococcus MA19 (70.7 mM, Miyake et al., 1997), as compared to 720 mM for Wautersia eutropha (Haywood et al, 1989). This low K m may aid the accumulation of PHB under conditions of low carbon flux through the photoautotrophic mechanism of cyanobacteria (Smith, 1983).…”

Section: Discussionsupporting

confidence: 76%

Studies on poly-β-hydroxybutyrate synthase activity of Nostoc muscorum

Sharma

Panda

Singh

et al. 2006

J. Gen. Appl. Microbiol.

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“…The activity of PHA synthase was determined by spectroscopic assay according to the methods described by Valentin and Steinbüchel (43). (R)-3HB-CoA was synthesized by the mixed anhydride method described by Haywood et al (11).…”

Section: Methodsmentioning

confidence: 99%

Cloning and analysis of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) biosynthesis genes of Aeromonas caviae

1997

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A 5.0-kbp EcoRV-EcoRI restriction fragment was cloned and analyzed from genomic DNA of Aeromonas caviae, a bacterium producing a copolyester of (R)-3-hydroxybutyrate (3HB) and (R)-3-hydroxyhexanoate (3HHx) [P(3HB-co-3HHx)] from alkanoic acids or oils. The nucleotide sequence of this region showed a 1,782-bp poly (3-hydroxyalkanoate) (PHA) synthase gene (phaC Ac [i.e., the phaC gene from A. caviae]) together with four open reading frames (ORF1, -3, -4, and -5) and one putative promoter region. The cloned fragments could not only complement PHA-negative mutants of Alcaligenes eutrophus and Pseudomonas putida, but also confer the ability to synthesize P(3HB-co-3HHx) from octanoate or hexanoate on the mutants' hosts. Furthermore, coexpression of ORF1 and ORF3 genes with phaC Ac in the A. eutrophus mutant resulted in a decrease in the polyester content of the cells. Escherichia coli expressing ORF3 showed (R)-enoyl-coenzyme A (CoA) hydratase activity, suggesting that (R)-3-hydroxyacyl-CoA monomer units are supplied via the (R)-specific hydration of enoyl-CoA in A. caviae. The transconjugant of the A. eutrophus mutant expressing only phaC Ac effectively accumulated P(3HB-co-3HHx) up to 96 wt% of the cellular dry weight from octanoate in one-step cultivation.The utilization of biological systems for production of biodegradable materials is becoming important as a solution of the problems concerning plastic waste and the global environment. Poly(3-hydroxyalkanoates) (PHA) are produced by a wide variety of bacteria as intracellular carbon-and energystorage materials from renewable carbon resources, such as sugars or plant oils (2,6,18,25). Since these bacterial PHA are biodegradable thermoplastics, they have attracted industrial attention as possible candidates for large-scale biotechnological products. At present, more than 90 different monomeric units have been found as constituents of PHA (37).Bacterial PHA can be divided into two groups, depending on the number of carbon atoms in the monomeric units (35). One group of bacteria, including Alcaligenes eutrophus, produces short-chain-length PHA with C 3 -to-C 5 monomer units, while the other group, including Pseudomonas oleovorans, synthesizes medium-chain-length PHA with C 6 -to-C 14 monomer units. Only a few reports are available for bacteria which can synthesize PHA consisting of both short-and medium-chainlength monomer units. For example, Rhodospirillum rubrum (3), Rhodocyclus gelatinosus (19), and Rhodococcus ruber (12) produce terpolymers consisting of C 4 , C 5 , and C 6 3-hydroxyalkanoate (3HA) units from hexanoate, and some pseudomonad strains accumulate PHA consisting of C 4 -to-C 12 3HA units (16,38). Our laboratory has found that a random copolymer of 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HHx), P(3HB-co-3HHx), is produced by Aeromonas caviae FA440 isolated from soil (7,32). This bacterium synthesizes the copolyester from alkanoic acids of even carbon numbers or from plant oils up to approximately 30 wt% of the cellular dry weight, with a 3HHx fra...

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“…In R. eutropha H16, the key component of PHB biosynthesis is the PHB synthase encoded by phaC1. The gene is constitutively expressed, and the enzyme occurs as a soluble protein only at the beginning of PHB biosynthesis; upon onset of PHB biosynthesis, the enzyme becomes granule-bound (Haywood et al, 1989;Gerngross et al, 1993). The constitutive expression of phaC1 is affirmed by the first K. Peplinski and others two transcription analyses presented in this study, comparing (i) transcriptomes from exponential growth phase with transcriptomes from the transition phase and (ii) transcriptomes from transition phase with transcriptomes from the stationary growth phase of R. eutropha H16.…”

Section: Correlation Between Transcriptomic and Proteomic Datamentioning

confidence: 99%

Genome-wide transcriptome analyses of the ‘Knallgas’ bacterium Ralstonia eutropha H16 with regard to polyhydroxyalkanoate metabolism

et al. 2010

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Ralstonia eutropha H16 is probably the best-studied 'Knallgas' bacterium and producer of poly(3-hydroxybutyrate) (PHB). Genome-wide transcriptome analyses were employed to detect genes that are differentially transcribed during PHB biosynthesis. For this purpose, four transcriptomes from different growth phases of the wild-type H16 and of the two PHB-negative mutants PHB " 4 and DphaC1 were compared: (i) cells from the exponential growth phase with cells that were in transition to stationary growth phase, and (ii) cells from the transition phase with cells from the stationary growth phase of R. eutropha H16, as well as (iii) cells from the transition phase of R. eutropha H16 with those from the transition phase of R. eutropha PHB " 4 and (iv) cells from the transition phase of R. eutropha DphaC1 with those from the transition phase of R. eutropha PHB " 4. Among a large number of genes exhibiting significant changes in transcription level, several genes within the functional class of lipid metabolism were detected. In strain H16, phaP3, accC2, fabZ, fabG and H16_A3307 exhibited a decreased transcription level in the stationary growth phase compared with the transition phase, whereas phaP1, H16_A3311, phaZ2 and phaZ6 were found to be induced in the stationary growth phase. Compared with PHB " 4, we found that phaA, phaB1, paaH1, H16_A3307, phaP3, accC2 and fabG were induced in the wildtype, and phaP1, phaP4, phaZ2 and phaZ6 exhibited an elevated transcription level in PHB " 4. In strain DphaC1, phaA and phaB1 were highly induced compared with PHB " 4. Additionally, the results of this study suggest that mutant strain PHB " 4 is defective in PHB biosynthesis and fatty acid metabolism. A significant downregulation of the two cbb operons in mutant strain PHB " 4 was observed. The putative polyhydroxyalkanoate (PHA) synthase phaC2 identified in strain H16 was further investigated by several functional analyses. Mutant PHB " 4 could be phenotypically complemented by expression of phaC2 from a plasmid; on the other hand, in the mutant H16DphaC1, no PHA production was observed. PhaC2 activity could not be detected in any experiment.

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The importance of PHB-synthase substrate specificity in polyhydroxyalkanoate synthesis by Alcaligenes eutrophus

Cited by 60 publications

References 4 publications

Studies on poly-β-hydroxybutyrate synthase activity of Nostoc muscorum

Studies on poly-β-hydroxybutyrate synthase activity of Nostoc muscorum

Cloning and analysis of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) biosynthesis genes of Aeromonas caviae

Genome-wide transcriptome analyses of the ‘Knallgas’ bacterium Ralstonia eutropha H16 with regard to polyhydroxyalkanoate metabolism

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