Morphological Change in Cellular Granule Formation of Poly[(<i>R</i>)-3-hydroxybutyrate] Caused by DNA-Binding-Related Mutations of an Autoregulated Repressor PhaR

Yamada, Miwa; Wakuda, Akiko; Taguchi, Seiichi

doi:10.1271/bbb.70038

Cited by 2 publications

(1 citation statement)

References 12 publications

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“…PhaR has been studied extensively in E. coli and Pseudomonas denitrificans where it can bind simultaneously to the PHB granule-associated protein PhaP and upstream of the phaP gene, thereby regulating PHB granule formation in a complex manner (Yamada et al 2013(Yamada et al , 2007a. Assuming a similar PHB cycle regulation in M. extorquens, the formation of PHB granules in AM1ΔphaR would be inhibited but the undesired synthesis of PHB from (3R)-hydroxybutyrylCoA catalyzed by PhaC is probably still existent.…”

Section: Discussionmentioning

confidence: 99%

High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains

Sonntag

Müller

Kiefer

et al. 2015

Appl Microbiol Biotechnol

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Bio-based production of dicarboxylic acids is an emerging research field with remarkable progress during the last decades. The recently established synthesis of the ethylmalonyl-CoA pathway (EMCP)-derived dicarboxylic acids, mesaconic acid and (2S)-methylsuccinic acid, from the alternative carbon source methanol (Sonntag et al., Appl Microbiol Biotechnol 98:4533-4544, 2014) gave a proof of concept for the sustainable production of hitherto biotechnologically inaccessible monomers. In this study, substantial optimizations of the process by different approaches are presented. Abolishment of mesaconic and (2S)-methylsuccinic acid reuptake from culture supernatant and a productivity increase were achieved by 30-fold decreased sodium ion availability in culture medium. Undesired flux from EMCP into polyhydroxybutyrate (PHB) cycle was hindered by the knockout of polyhydroxyalkanoate synthase phaC which was concomitant with 5-fold increased product concentrations. However, frequently occurring suppressors of strain ΔphaC lost their beneficial properties probably due to redirected channeling of acetyl-CoA. Pool sizes of the product precursors were increased by exploiting the presence of two cobalt-dependent mutases in the EMCP: Fine-tuned growth-limiting cobalt concentrations led to 16-fold accumulation of mesaconyl- and (2S)-methylsuccinyl-CoA which in turn resulted in 6-fold increased concentrations of mesaconic and (2S)-methylsuccinic acids, with a combined titer of 0.65 g/l, representing a yield of 0.17 g/g methanol. This work represents an important step toward an industrially relevant production of ethylmalonyl-CoA pathway-derived dicarboxylic acids and the generation of a stable PHB synthesis negative Methylobacterium extorquens strain.

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Section: Discussionmentioning

confidence: 99%

High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains

Sonntag

Müller

Kiefer

et al. 2015

Appl Microbiol Biotechnol

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Enhancement of Stress Tolerance in the Polyhydroxyalkanoate Producers without Mobilization of the Accumulated Granules

Goh

Purama

Sudesh

2013

Appl Biochem Biotechnol

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Poly(3-hydroxybutyrate) [P(3HB)], a polymer belonging to the polyhydroxyalkanoate (PHA) family, is accumulated by numerous bacteria as carbon and energy storage material. The mobilization of accumulated P(3HB) is associated with increased stress and starvation tolerance. However, the potential function of accumulated copolymer such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] remained unknown. In this study, Delftia acidovorans DS 17 was used to evaluate the contributions of P(3HB) and P(3HB-co-3HV) granules during simulated exogenous carbon deprivation on cell survival by transferring cells with PHAs to carbon-free mineral salt medium supplemented with 1% (w/v) nitrogen source. By mobilizing the intracellular P(3HB) and P(3HB-co-3HV) at 11 and 40 mol% 3HV compositions, the cells survived starvation. Surprisingly, D. acidovorans containing P(3HB-co-94 mol% 3HV) also survived although the mobilization was not as effective. Similarly, recombinant Escherichia coli pGEM-T::phbCAB(Cn) (harboring the PHA biosynthesis genes of Cupriavidus necator) containing P(3HB) granules had a higher viable cell counts compared to those without P(3HB) granules but without any P(3HB) mobilization when exposed to oxidative stress by photoactivated titanium dioxide. This study provided strong evidence that enhancement of stress tolerance in PHA producers can be achieved without mobilization of the previously accumulated granules. Instead, PHA biosynthesis may improve bacterial survival via multiple mechanisms.

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Morphological Change in Cellular Granule Formation of Poly[(R)-3-hydroxybutyrate] Caused by DNA-Binding-Related Mutations of an Autoregulated Repressor PhaR

Cited by 2 publications

References 12 publications

High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains

High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains

Enhancement of Stress Tolerance in the Polyhydroxyalkanoate Producers without Mobilization of the Accumulated Granules

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