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

Abe, Tomoko; Kobayashi, T; Saito, Terumi

doi:10.1128/jb.187.20.6982-6990.2005

Cited by 64 publications

(65 citation statements)

References 47 publications

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“…It is inactive against p-nitrophenylpalmitate, dPHB, tributyrin, and triolein. The esterase activity of the B. thuringiensis PhaZ toward p-nitrophenylbutyrate is comparable to that shown by PhaZa1 of R. eutropha but is much weaker than that shown by PhaZd of R. eutropha (1). Since neither esterase activity toward tributyrin nor lipase activity toward triolein was In contrast to other known intracellular PHB depolymerases, the B. thuringiensis PhaZ generates much more 3HB monomers as hydrolytic product.…”

Section: Discussionmentioning

confidence: 80%

“…The intracellular PhaZd of Ralstonia eutropha H16 shows similarity with the type I catalytic domain of extracellular PHB depolymerases from bacteria such as R. pickettii T1 and Paucimonas lemoignei (17) and produces various 3HB oligomers from amorphous PHB as hydrolytic products. 3HB monomer was rarely detected as a hydrolytic product (1). The periplasm-located PHB depolymerase of R. rubrum (10) shows similarity with the type II catalytic domain of extracellular PHB depolymerases from bacteria such as Acidovorax sp.…”

Section: Discussionmentioning

confidence: 99%

“…While the extracellular degradation of denatured semicrystalline PHB (dPHB) has been clarified in many bacteria (16,17,37), not much is known about intracellular mobilization of PHB. So far, only a few novel intracellular PHB depolymerase (PhaZ) genes have been identified and characterized (1,33). phaZa1 (formerly phaZ1) of Ralstonia eutropha H16, which was the first cloned intracellular PHB depolymerase gene (33), encodes a protein with no classical lipase box (G-X-S-X-G) (15).…”

mentioning

confidence: 99%

“…These PhaZa1 homologs also lack the typical lipase box motif. Recently, a novel intracellular PHB depolymerase gene (phaZd) was cloned from Ralstonia eutropha H16 (1). phaZd encodes a protein which shows similarity with the type I catalytic domain of extracellular PHB depolymerases from bacteria such as Ralstonia pickettii T1 and Paucimonas lemoignei (17).…”

mentioning

confidence: 99%

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Identification and Characterization of the Bacillus thuringiensi s phaZ Gene, Encoding New Intracellular Poly-3-Hydroxybutyrate Depolymerase

Tseng¹,

Chen²,

Shaw³

2006

J Bacteriol

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A gene that codes for a novel intracellular poly-3-hydroxybutyrate (PHB) depolymerase has now been identified in the genome of Bacillus thuringiensis subsp. israelensis ATCC 35646. This gene, previously annotated as a hypothetical 3-oxoadipate enol-lactonase (PcaD) gene and now designated phaZ, encodes a protein that shows no significant similarity with any known PHB depolymerase. Purified His-tagged PhaZ could efficiently degrade trypsin-activated native PHB granules as well as artificial amorphous PHB granules and release 3-hydroxybutyrate monomer as a hydrolytic product, but it could not hydrolyze denatured semicrystalline PHB. In contrast, purified His-tagged PcaD of Pseudomonas putida was unable to degrade trypsin-activated native PHB granules and artificial amorphous PHB granules. The B. thuringiensis PhaZ was inactive against pnitrophenylpalmitate, tributyrin, and triolein. Sonication supernatants of the wild-type B. thuringiensis cells exhibited a PHB-hydrolyzing activity in vitro, whereas those prepared from a phaZ mutant lost this activity. The phaZ mutant showed a higher PHB content than the wild type at late stationary phase of growth in a nutrient-rich medium, indicating that this PhaZ can function as a PHB depolymerase in vivo. PhaZ contains a lipase box-like sequence (G-W-S 102 -M-G) but lacks a signal peptide. A purified His-tagged S102A variant had lost the PHB-hydrolyzing activity. Taken together, these results indicate that B. thuringiensis harbors a new type of intracellular PHB depolymerase.

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Identification and Characterization of the Bacillus thuringiensi s phaZ Gene, Encoding New Intracellular Poly-3-Hydroxybutyrate Depolymerase

Tseng¹,

Chen²,

Shaw³

2006

J Bacteriol

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“…PhaZa1 degrades nPHB to 3HB-CoA in the presence of CoA (8,9), whereas PhaZb and PhaZc mainly hydrolyze 3HB oligomer to 3HB (12,13). PhaZd degrades artificial PHB (aPHB) and nPHB granules and releases mainly 3HB oligomer with only a small amount of 3HB monomer (6,7). A genetic analysis showed the PHB depolymerase redundancy in R. eutropha H16.…”

mentioning

confidence: 99%

A Patatin-Like Protein Associated with the Polyhydroxyalkanoate (PHA) Granules of Haloferax mediterranei Acts as an Efficient Depolymerase in the Degradation of Native PHA

Liu

Hou

Cai

et al. 2015

Appl Environ Microbiol

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cThe key enzymes and pathways involved in polyhydroxyalkanoate (PHA) biosynthesis in haloarchaea have been identified in recent years, but the haloarchaeal enzymes for PHA degradation remain unknown. In this study, a patatin-like PHA depolymerase, PhaZh1, was determined to be located on the PHA granules in the haloarchaeon Haloferax mediterranei. PhaZh1 hydrolyzed the native PHA (nPHA) [including native polyhydroxybutyrate (nPHB) and native poly(3-hydroxybutyrateco-3-hydroxyvalerate) (nPHBV) in this study] granules in vitro with 3-hydroxybutyrate (3HB) monomer as the primary product. The site-directed mutagenesis of PhaZh1 indicated that Gly 16 , Ser 47 (in a classical lipase box, G-X-S 47 -X-G), and Asp 195 of this depolymerase were essential for its activity in nPHA granule hydrolysis. Notably, phaZh1 and bdhA (encoding putative 3HB dehydrogenase) form a gene cluster (HFX_6463 to _6464) in H. mediterranei. The 3HB monomer generated from nPHA degradation by PhaZh1 could be further converted into acetoacetate by BdhA, indicating that PhaZh1-BdhA may constitute the first part of a PHA degradation pathway in vivo. Interestingly, although PhaZh1 showed efficient activity and was most likely the key enzyme in nPHA granule hydrolysis in vitro, the knockout of phaZh1 had no significant effect on the intracellular PHA mobilization, implying the existence of an alternative PHA mobilization pathway(s) that functions effectively within the cells of H. mediterranei. Therefore, identification of this patatin-like depolymerase of haloarchaea may provide a new strategy for producing the high-value-added chiral compound (R)-3HB and may also shed light on the PHA mobilization in haloarchaea. P olyhydroxyalkanoate (PHA) is accumulated in the form of granules and serves as storage compound of carbon and energy in bacteria (1) and archaea (2) during growth in the presence of excess carbon sources. Several proteins, which are known as PHA granule-associated proteins (PGAPs), are embedded on or attached to the PHA granules. These include PHA synthases, phasins, regulatory proteins, and depolymerases (3). A PHA-accumulating host may utilize the accumulated PHA for growth and survival under conditions of carbon starvation (4). PHA depolymerase (PhaZ) is the key enzyme that functions in PHA mobilization.In bacteria, PHA depolymerases are grouped into two classes: intracellular (catalyzing the degradation of endogenous PHA) (iPhaZ) and extracellular (catalyzing the degradation of exogenous PHA) (ePhaZ) PHA depolymerases (5). The extracellular PHA depolymerase degradation process is well known, but the mechanism underlying the metabolic pathway and regulation of PHA degradation in vivo remains poorly understood (5). Native polyhydroxybutyrate (nPHB) is degraded by iPhaZs in vitro to 3-hydroxybutyrate (3HB) (6, 7) or 3-hydroxybutyryl-coenzyme A (3HB-CoA) in the presence of CoA (8, 9). The PHB degradation product, 3HB-CoA, is the precursor of PHB synthesis; hence, the simultaneous synthesis and mobilization of PHB (10, 11) (8). Notably, th...

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Polyhydroxyalkanoates

Zainab-L

Yean

Sudesh

2018

Kirk-Othmer Encyclopedia of Chemical Technology

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Plastic waste accumulation in the environment has become a global issue. The search for alternative materials motivated the research on polyhydroxyalkanoates (PHAs), a biopolymer having properties similar to polypropylene. PHAs are biodegradable, biocompatible, and environment‐friendly thermoplastics, and therefore, a potential substitute for some nonbiodegradable commodity plastics. The favorable plastic‐like properties of PHA give rise to applications in various areas. PHAs are expensive compared to conventional plastics, but improved PHA biosynthesis has reduced the cost significantly. Current research is focused on utilization of low cost substrates, development of simple and cost‐effective extraction methods, and use of mixed microbial cultures and recombinant microbial strains in order to achieve economically feasible production of PHAs.This article provides background on PHAs, their properties, and biosynthesis. Large‐scale production, commercialization, application, and sustainability considerations are presented and discussed. Interesting features of PHAs and their role from an industrial ecology perspective are highlighted.

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

Abstract: A novel intracellular poly(3-hydroxybutyrate) (PHB) depolymerase (PhaZd) of Wautersia eutropha (formerly

Cited by 64 publications

References 47 publications

Identification and Characterization of the Bacillus thuringiensi s phaZ Gene, Encoding New Intracellular Poly-3-Hydroxybutyrate Depolymerase

Identification and Characterization of the Bacillus thuringiensi s phaZ Gene, Encoding New Intracellular Poly-3-Hydroxybutyrate Depolymerase

A Patatin-Like Protein Associated with the Polyhydroxyalkanoate (PHA) Granules of Haloferax mediterranei Acts as an Efficient Depolymerase in the Degradation of Native PHA

Polyhydroxyalkanoates

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