Novel Intracellular 3-Hydroxybutyrate-Oligomer Hydrolase in Wautersia eutropha H16

ABSTRACT Wautersia eutropha H16 (formerly Ralstonia eutropha) mobilizes intracellularly accumulated poly(3-hydroxybutyrate) (PHB) with intracellular poly(3-hydroxybutyrate) depolymerases. In this study, a novel intracellular 3-hydroxybutyrate-oligomer hydrolase (PhaZc) gene was cloned and overexpressed in Escherichia coli. Then PhaZc was purified and characterized. Immunoblot analysis with polyclonal antiserum against PhaZc revealed that most PhaZc is present in the cytosolic fraction and a small amount is present in the poly(3-hydroxybutyrate) inclusion bodies of W. eutropha. PhaZc degraded various 3-hydroxybutyrate oligomers at a high specific activity and artificial amorphous poly(3-hydroxybutyrate) at a lower specific activity. Native PHB granules and semicrystalline PHB were not degraded by PhaZc. A PhaZ deletion mutation enhanced the deposition of PHB in the logarithmic phase in nutrient-rich medium. PhaZc differs from the hydrolases of W. eutropha previously reported and is a novel type of intracellular 3-hydroxybutyrate-oligomer hydrolase, and it participates in the mobilization of PHB along with other hydrolases.

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Properties of a Novel Intracellular Poly(3-Hydroxybutyrate) Depolymerase with High Specific Activity (PhaZd) in Wautersia eutropha H16

Journal of Bacteriology ◽

10.1128/jb.187.20.6982-6990.2005 ◽

2005 ◽

Vol 187 (20) ◽

pp. 6982-6990 ◽

Cited By ~ 53

Author(s):

Tomoko Abe ◽

Teruyuki Kobayashi ◽

Terumi Saito

Keyword(s):

Catalytic Domain ◽

Ralstonia Eutropha ◽

Specific Activity ◽

High Specific Activity ◽

Catalytic Triad ◽

Culture Conditions ◽

Phb Depolymerase ◽

Wautersia Eutropha ◽

Extracellular Phb Depolymerase ◽

Intracellular Phb Depolymerase

ABSTRACT A novel intracellular poly(3-hydroxybutyrate) (PHB) depolymerase (PhaZd) of Wautersia eutropha (formerly Ralstonia eutropha) H16 which shows similarity with the catalytic domain of the extracellular PHB depolymerase in Ralstonia pickettii T1 was identified. The positions of the catalytic triad (Ser190-Asp266-His330) and oxyanion hole (His108) in the amino acid sequence of PhaZd deduced from the nucleotide sequence roughly accorded with those of the extracellular PHB depolymerase of R. pickettii T1, but a signal peptide, a linker domain, and a substrate binding domain were missing. The PhaZd gene was cloned and the gene product was purified from Escherichia coli. The specific activity of PhaZd toward artificial amorphous PHB granules was significantly greater than that of other known intracellular PHB depolymerase or 3-hydroxybutyrate (3HB) oligomer hydrolases of W. eutropha H16. The enzyme degraded artificial amorphous PHB granules and mainly released various 3-hydroxybutyrate oligomers. PhaZd distributed nearly equally between PHB inclusion bodies and the cytosolic fraction. The amount of PHB was greater in phaZd deletion mutant cells than the wild-type cells under various culture conditions. These results indicate that PhaZd is a novel intracellular PHB depolymerase which participates in the mobilization of PHB in W. eutropha H16 along with other PHB depolymerases.

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PhaM Is the Physiological Activator of Poly(3-Hydroxybutyrate) (PHB) Synthase (PhaC1) in Ralstonia eutropha

Applied and Environmental Microbiology ◽

10.1128/aem.02935-13 ◽

2013 ◽

Vol 80 (2) ◽

pp. 555-563 ◽

Cited By ~ 36

Author(s):

Daniel Pfeiffer ◽

Dieter Jendrossek

Keyword(s):

De Novo ◽

Ralstonia Eutropha ◽

Specific Activity ◽

High Specific Activity ◽

Size Exclusion ◽

Lag Phase ◽

Granule Formation ◽

Content Type ◽

Phb Synthase

ABSTRACTPoly(3-hydroxybutyrate) (PHB) synthase (PhaC1) is the key enzyme of PHB synthesis inRalstonia eutrophaand other PHB-accumulating bacteria and catalyzes the polymerization of 3-hydroxybutyryl-CoA to PHB. Activity assays ofR. eutrophaPHB synthase are characterized by the presence of lag phases and by low specific activity. It is assumed that the lag phase is caused by the time necessary to convert the inactive PhaC1 monomer into the active dimeric form by an unknown priming process. The lag phase can be reduced by addition of nonionic detergents such as hecameg [6-O-(N-heptyl-carbamoyl)-methyl-α-d-glucopyranoside], which apparently accelerates the formation of PhaC1 dimers. We identified the PHB granule-associated protein (PGAP) PhaM as the natural primer (activator) of PHB synthase activity. PhaM was recently discovered as a novel type of PGAP with multiple functions in PHB metabolism. Addition of PhaM to PHB synthase assays resulted in immediate polymerization of 3HB coenzyme A with high specific activity and without a significant lag phase. The effect of PhaM on (i) PhaC1 activity, (ii) oligomerization of PhaC1, (iii) complex formation with PhaC1, and (iv) PHB granule formationin vitroandin vivowas shown by cross-linking experiments of purified proteins (PhaM, PhaC1) with glutardialdehyde, by size exclusion chromatography, and by fluorescence microscopic detection ofde novo-synthesized PHB granules.

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Effects of Heparin Oligosaccharides with High Affinity for Antithrombin III in Experimental Venous Thrombosis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657178 ◽

1982 ◽

Vol 47 (03) ◽

pp. 244-248 ◽

Cited By ~ 47

Author(s):

D P Thomas ◽

Rosemary E Merton ◽

T W Barrowcliffe ◽

L Thunberg ◽

U Lindahl

Keyword(s):

Antithrombin Iii ◽

Specific Activity ◽

High Specific Activity ◽

Factor Xa ◽

Blood Levels ◽

Thrombin Time ◽

High Affinity ◽

Very High

SummaryThe in vitro and in vivo characteristics of two oligosaccharide heparin fragments have been compared to those of unfractionated mucosal heparin. A decasaccharide fragment had essentially no activity by APTT or calcium thrombin time assays in vitro, but possessed very high specific activity by anti-Factor Xa assays. When injected into rabbits at doses of up to 80 ¼g/kg, this fragment was relatively ineffective in impairing stasis thrombosis despite producing high blood levels by anti-Xa assays. A 16-18 monosaccharide fragment had even higher specific activity (almost 2000 iu/mg) by chromogenic substrate anti-Xa assay, with minimal activity by APTT. When injected in vivo, this fragment gave low blood levels by APTT, very high anti-Xa levels, and was more effective in preventing thrombosis than the decasaccharide fragment. However, in comparison with unfractionated heparin, the 16-18 monosaccharide fragment was only partially effective in preventing thrombosis, despite producing much higher blood levels by anti-Xa assays.It is concluded that the high-affinity binding of a heparin fragment to antithrombin III does not by itself impair venous thrombogenesis, and that the anti-Factor Xa activity of heparin is only a partial expression of its therapeutic potential.

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Autoprothrombin C Activity from Prothrombin with Snake Venom or Trypsin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655440 ◽

1962 ◽

Vol 08 (03) ◽

pp. 425-433 ◽

Cited By ~ 1

Author(s):

Ewa Marciniak ◽

Edmond R Cole ◽

Walter H Seegers

Keyword(s):

Snake Venom ◽

Thrombolytic Agent ◽

Sodium Citrate ◽

Specific Activity ◽

High Specific Activity ◽

Citrate Solution ◽

Clotting Factors ◽

Activation Products ◽

Russell’S Viper ◽

Autoprothrombin C

SummarySuitable conditions were found for the generation of autoprothrombin C from purified prothrombin with the use of Russell’s viper venom or trypsin. DEAE chromatographed prothrombin is structurally altered and has never been found to yield autoprothrombin C and also did not yield it when Russell’s viper venom or trypsin were used. Autoprothrombin C is derived from prothrombin with tissue extract thromboplastin, but not in large amounts with the intrinsic clotting factors. With the latter thrombin and autoprothrombin III are the chief activation products. Autoprothrombin III concentrates were prepared from serum and upon activation with 25% sodium citrate solution or with Russell’s viper venom large amounts of autoprothrombin C were obtained, and this was of high specific activity. Theoretically trypsin is not a thrombolytic agent, but on the contrary should lead to intravascular clotting.

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