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de Koning EA, Panjalingam M, Tran J, Eckhart MR, Dahlberg PD, Shapiro L. The PHB Granule Biogenesis Pathway in Caulobacter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.06.548030. [PMID: 37461544 PMCID: PMC10350054 DOI: 10.1101/2023.07.06.548030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
PHB granules are bacterial organelles that store excess carbohydrates in the form of water-insoluble polyhydroxybutyrate (PHB). The PHB polymerase, phasin (a small amphipathic protein), and active PHB synthesis are essential for the formation of mature PHB granules in Caulobacter crescentus. Granule formation was found to be initiated by the condensation of self-associating PHB polymerase-GFP into foci, closely followed by the recruitment and condensation of phasin-mCherry. Following the active synthesis of PHB and granule maturation, the polymerase dissociates from mature granules and the PHB depolymerase is recruited to the granule. The polymerase directly binds phasin in vitro through its intrinsically disordered N-terminal domain. Thus, granule biogenesis is initiated and controlled by the action of a PHB polymerase and an associated helper protein, phasin, that together synthesize the hydrophobic granule's content while forming the granules protein boundary.
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Martinez S, Humery A, Groleau MC, Déziel E. Quorum Sensing Controls Both Rhamnolipid and Polyhydroxyalkanoate Production in Burkholderia thailandensis Through ScmR Regulation. Front Bioeng Biotechnol 2020; 8:1033. [PMID: 33015011 PMCID: PMC7498548 DOI: 10.3389/fbioe.2020.01033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/10/2020] [Indexed: 11/13/2022] Open
Abstract
Rhamnolipids are surface-active agents of microbial origin used as alternatives to synthetic surfactants. Burkholderia thailandensis is a non-pathogenic rhamnolipid-producing bacterium that could represent an interesting candidate for use in commercial processes. However, current bioprocesses for rhamnolipid production by this bacterium are not efficient enough, mainly due to low yields. Since regulation of rhamnolipid biosynthesis in B. thailandensis remains poorly understood, identifying new regulatory factors could help increase the production of these valuable metabolites. We performed a random transposon mutagenesis screening to identify genes directing rhamnolipid production in B. thailandensis E264. The most efficient rhamnolipid producer we identified harbored an inactivating transposon insertion in the scmR gene, which was recently described to encode as a secondary metabolite regulator in B. thailandensis. We investigated the impact of scmR loss on rhamnolipid biosynthesis and cell growth. Because biosynthesis of rhamnolipids and polyhydroxyalkanoates (PHAs) could share the same pool of lipid precursors, we also investigate the effect of ScmR on PHA production. We found that production of both rhamnolipids and PHAs are modulated by ScmR during the logarithmic growth phase and demonstrate that ScmR downregulates the production of rhamnolipids by affecting the expression of both rhl biosynthetic operons. Furthermore, our results indicate that PHA biosynthesis is reduced in the scmR- mutant, as ScmR promotes the transcription of the phaC and phaZ genes. By studying the relationship between ScmR and quorum sensing (QS) regulation we reveal that QS acts as an activator of scmR transcription. Finally, we pinpoint the QS-3 system as being involved in the regulation of rhamnolipid and PHA biosynthesis. We conclude that ScmR negatively affects rhamnolipid production, whereas it positively impacts PHAs biosynthesis. This could provide an interesting approach for future strain engineering, leading to improved yields of these valuable metabolites.
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Affiliation(s)
- Sarah Martinez
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Adeline Humery
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Marie-Christine Groleau
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
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3
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Characterization of an intracellular poly(3-hydroxyalkanoate) depolymerase from the soil bacterium, Pseudomonas putida LS46. Polym Degrad Stab 2020. [DOI: 10.1016/j.polymdegradstab.2020.109127] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kelly CL. Degrading an enzyme to increase its product: a novel approach to decoupling biosynthesis and growth. Synth Biol (Oxf) 2019; 4:ysz001. [PMID: 32995529 PMCID: PMC7445787 DOI: 10.1093/synbio/ysz001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
- Ciarán L Kelly
- Agriculture and Engineering, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
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Mohamed RA, Salleh AB, Leow TC, Yahaya NM, Abdul Rahman MB. Site-directed mutagenesis: role of lid region for T1 lipase specificity. Protein Eng Des Sel 2018; 31:221-229. [DOI: 10.1093/protein/gzy023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 08/27/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Rauda A Mohamed
- Laboratory of Enzyme Technology, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Abu Bakar Salleh
- Laboratory of Enzyme Technology, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Thean Chor Leow
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Normi M Yahaya
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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Pakalapati H, Chang CK, Show PL, Arumugasamy SK, Lan JCW. Development of polyhydroxyalkanoates production from waste feedstocks and applications. J Biosci Bioeng 2018; 126:282-292. [DOI: 10.1016/j.jbiosc.2018.03.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 03/15/2018] [Accepted: 03/23/2018] [Indexed: 12/30/2022]
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Kutralam-Muniasamy G, Peréz-Guevara F. Genome characteristics dictate poly-R-(3)-hydroxyalkanoate production in Cupriavidus necator H16. World J Microbiol Biotechnol 2018; 34:79. [DOI: 10.1007/s11274-018-2460-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/19/2018] [Indexed: 11/28/2022]
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Mohamed RA, Salleh AB, Leow ATC, Yahaya NM, Abdul Rahman MB. Ability of T1 Lipase to Degrade Amorphous P(3HB): Structural and Functional Study. Mol Biotechnol 2018; 59:284-293. [PMID: 28580552 DOI: 10.1007/s12033-017-0012-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
An enzyme with broad substrate specificity would be an asset for industrial application. T1 lipase apparently has the same active site residues as polyhydroxyalkanoates (PHA) depolymerase. Sequences of both enzymes were studied and compared, and a conserved lipase box pentapeptide region around the nucleophilic serine was detected. The alignment of 3-D structures for both enzymes showed their active site residues were well aligned with an RMSD value of 1.981 Å despite their sequence similarity of only 53.8%. Docking of T1 lipase with P(3HB) gave forth high binding energy of 5.4 kcal/mol, with the distance of 4.05 Å between serine hydroxyl (OH) group of TI lipase to the carbonyl carbon of the substrate, similar to the native PhaZ7 Pl . This suggests the possible ability of T1 lipase to bind P(3HB) in its active site. The ability of T1 lipase in degrading amorphous P(3HB) was investigated on 0.2% (w/v) P(3HB) plate. Halo zone was observed around the colony containing the enzyme which confirms that T1 lipase is indeed able to degrade amorphous P(3HB). Results obtained in this study highlight the fact that T1 lipase is a versatile hydrolase enzyme which does not only record triglyceride degradation activity but amorphous P(3HB) degradation activity as well.
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Affiliation(s)
- Rauda A Mohamed
- Laboratory of Enzyme Technology, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Abu Bakar Salleh
- Laboratory of Enzyme Technology, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
| | - Adam Thean Chor Leow
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Normi M Yahaya
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
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Inactivation of an intracellular poly-3-hydroxybutyrate depolymerase of Azotobacter vinelandii allows to obtain a polymer of uniform high molecular mass. Appl Microbiol Biotechnol 2018; 102:2693-2707. [DOI: 10.1007/s00253-018-8806-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 01/16/2018] [Accepted: 01/18/2018] [Indexed: 01/20/2023]
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Sadykov MR, Ahn JS, Widhelm TJ, Eckrich VM, Endres JL, Driks A, Rutkowski GE, Wingerd KL, Bayles KW. Poly(3-hydroxybutyrate) fuels the tricarboxylic acid cycle andde novolipid biosynthesis duringBacillus anthracissporulation. Mol Microbiol 2017; 104:793-803. [DOI: 10.1111/mmi.13665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Marat R. Sadykov
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Jong-Sam Ahn
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Todd J. Widhelm
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Valerie M. Eckrich
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Jennifer L. Endres
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Adam Driks
- Department of Microbiology and Immunology; Loyola University Chicago, Stritch School of Medicine; Maywood IL 60153 USA
| | | | | | - Kenneth W. Bayles
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
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Higuchi-Takeuchi M, Morisaki K, Toyooka K, Numata K. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria. PLoS One 2016; 11:e0160981. [PMID: 27513570 PMCID: PMC4981452 DOI: 10.1371/journal.pone.0160981] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/27/2016] [Indexed: 12/24/2022] Open
Abstract
Polyhydroxyalkanoate (PHA) is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide.
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Affiliation(s)
- Mieko Higuchi-Takeuchi
- Enzyme Research Team, Biomass Engineering Research Division, RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
| | - Kumiko Morisaki
- Enzyme Research Team, Biomass Engineering Research Division, RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
| | - Kiminori Toyooka
- Mass Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
| | - Keiji Numata
- Enzyme Research Team, Biomass Engineering Research Division, RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
- * E-mail:
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Wang X, Li Z, Li X, Qian H, Cai X, Li X, He J. Poly-β-hydroxybutyrate Metabolism Is Unrelated to the Sporulation and Parasporal Crystal Protein Formation in Bacillus thuringiensis. Front Microbiol 2016; 7:836. [PMID: 27379025 PMCID: PMC4908106 DOI: 10.3389/fmicb.2016.00836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 05/18/2016] [Indexed: 01/24/2023] Open
Abstract
Poly-3-hydroxybutyrate (PHB) is a natural polymer synthesized by many bacteria as a carbon-energy storage material. It was accumulated maximally prior to the spore formation but was degraded during the process of sporulation in Bacillus thuringiensis. Intriguingly, B. thuringiensis also accumulates large amounts of insecticidal crystal proteins (ICPs) during sporulation, which requires considerable input of carbon and energy sources. How PHB accumulation affects sporulation and ICP formation remains unclear to date. Intuitively, one would imagine that accumulated PHB provides the energy required for ICP formation. Yet our current data indicate that this is not the case. First, growth curves of the deletion mutants of phaC (encoding the PHB synthase) and phaZ (encoding the PHB depolymerase) were found to be similar to the parent strain BMB171; no difference in growth rate could be observed. In addition we further constructed the cry1Ac10 ICP gene overexpression strains of BMB171 (BMB171-cry), as well as its phaC and phaZ deletion mutants ΔphaC-cry and ΔphaZ-cry to compare their spore and ICP production rates. Again, not much change of ICP production was observed among these strains either. In fact, PHB was still degraded in most ΔphaZ-cry cells as observed by transmission electron microscopy. Together these results indicated that there is no direct association between the PHB accumulation and the sporulation and ICP formation in B. thuringiensis. Some other enzymes for PHB degradation or other energy source may be responsible for the sporulation and/or ICP formation in B. thuringiensis.
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Affiliation(s)
- Xun Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Zhou Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Xin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Hongliang Qian
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Xia Cai
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Xinfeng Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China; Key Laboratory of Agro-Microbial Resource and Development, Ministry of AgricultureWuhan, China
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A study on the relation between poly(3-hydroxybutyrate) depolymerases or oligomer hydrolases and molecular weight of polyhydroxyalkanoates accumulating in Cupriavidus necator H16. J Biotechnol 2016; 227:94-102. [DOI: 10.1016/j.jbiotec.2016.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 01/23/2023]
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Bresan S, Sznajder A, Hauf W, Forchhammer K, Pfeiffer D, Jendrossek D. Polyhydroxyalkanoate (PHA) Granules Have no Phospholipids. Sci Rep 2016; 6:26612. [PMID: 27222167 PMCID: PMC4879537 DOI: 10.1038/srep26612] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/05/2016] [Indexed: 12/11/2022] Open
Abstract
Polyhydroxybutyrate (PHB) granules, also designated as carbonosomes, are supra-molecular complexes in prokaryotes consisting of a PHB polymer core and a surface layer of structural and functional proteins. The presence of suspected phospholipids in the surface layer is based on in vitro data of isolated PHB granules and is often shown in cartoons of the PHB granule structure in reviews on PHB metabolism. However, the in vivo presence of a phospholipid layer has never been demonstrated. We addressed this topic by the expression of fusion proteins of DsRed2EC and other fluorescent proteins with the phospholipid-binding domain (LactC2) of lactadherin in three model organisms. The fusion proteins specifically localized at the cell membrane of Ralstonia eutropha but did not co-localize with PHB granules. The same result was obtained for Pseudomonas putida, a species that accumulates another type of polyhydroxyalkanoate (PHA) granules related to PHB. Notably, DsRed2EC-LactC2 expressed in Magnetospirillum gryphiswaldense was detected at the position of membrane-enclosed magnetosome chains and at the cytoplasmic membrane but not at PHB granules. In conclusion, the carbonosomes of representatives of α-proteobacteria, β-proteobacteria and γ-proteobacteria have no phospholipids in vivo and we postulate that the PHB/PHA granule surface layers in natural producers generally are free of phospholipids and consist of proteins only.
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Affiliation(s)
| | - Anna Sznajder
- Institute of Microbiology, University Stuttgart, Germany
| | - Waldemar Hauf
- Department of Organismic Interactions, Eberhard Karls Universität Tübingen, Germany
| | - Karl Forchhammer
- Department of Organismic Interactions, Eberhard Karls Universität Tübingen, Germany
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Comparative proteome analysis reveals four novel polyhydroxybutyrate (PHB) granule-associated proteins in Ralstonia eutropha H16. Appl Environ Microbiol 2014; 81:1847-58. [PMID: 25548058 DOI: 10.1128/aem.03791-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Identification of proteins that were present in a polyhydroxybutyrate (PHB) granule fraction isolated from Ralstonia eutropha but absent in the soluble, membrane, and membrane-associated fractions revealed the presence of only 12 polypeptides with PHB-specific locations plus 4 previously known PHB-associated proteins with multiple locations. None of the previously postulated PHB depolymerase isoenzymes (PhaZa2 to PhaZa5, PhaZd1, and PhaZd2) and none of the two known 3-hydroxybutyrate oligomer hydrolases (PhaZb and PhaZc) were significantly present in isolated PHB granules. Four polypeptides were found that had not yet been identified in PHB granules. Three of the novel proteins are putative α/β-hydrolases, and two of those (A0671 and B1632) have a PHB synthase/depolymerase signature. The third novel protein (A0225) is a patatin-like phospholipase, a type of enzyme that has not been described for PHB granules of any PHB-accumulating species. No function has been ascribed to the fourth protein (A2001), but its encoding gene forms an operon with phaB2 (acetoacetyl-coenzyme A [CoA] reductase) and phaC2 (PHB synthase), and this is in line with a putative function in PHB metabolism. The localization of the four new proteins at the PHB granule surface was confirmed in vivo by fluorescence microscopy of constructed fusion proteins with enhanced yellow fluorescent protein (eYFP). Deletion of A0671 and B1632 had a minor but detectable effect on the PHB mobilization ability in the stationary growth phase of nutrient broth (NB)-gluconate cells, confirming the functional involvement of both proteins in PHB metabolism.
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Eggers J, Steinbüchel A. Impact of Ralstonia eutropha's poly(3-Hydroxybutyrate) (PHB) Depolymerases and Phasins on PHB storage in recombinant Escherichia coli. Appl Environ Microbiol 2014; 80:7702-9. [PMID: 25281380 PMCID: PMC4249218 DOI: 10.1128/aem.02666-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/29/2014] [Indexed: 11/20/2022] Open
Abstract
The model organism for polyhydroxybutyrate (PHB) biosynthesis, Ralstonia eutropha H16, possesses multiple isoenzymes of granules coating phasins as well as of PHB depolymerases, which degrade accumulated PHB under conditions of carbon limitation. In this study, recombinant Escherichia coli BL21(DE3) strains were used to study the impact of selected PHB depolymerases of R. eutropha H16 on the growth behavior and on the amount of accumulated PHB in the absence or presence of phasins. For this purpose, 20 recombinant E. coli BL21(DE3) strains were constructed, which harbored a plasmid carrying the phaCAB operon from R. eutropha H16 to ensure PHB synthesis and a second plasmid carrying different combinations of the genes encoding a phasin and a PHB depolymerase from R. eutropha H16. It is shown in this study that the growth behavior of the respective recombinant E. coli strains was barely affected by the overexpression of the phasin and PHB depolymerase genes. However, the impact on the PHB contents was significantly greater. The strains expressing the genes of the PHB depolymerases PhaZ1, PhaZ2, PhaZ3, and PhaZ7 showed 35% to 94% lower PHB contents after 30 h of cultivation than the control strain. The strain harboring phaZ7 reached by far the lowest content of accumulated PHB (only 2.0% [wt/wt] PHB of cell dry weight). Furthermore, coexpression of phasins in addition to the PHB depolymerases influenced the amount of PHB stored in cells of the respective strains. It was shown that the phasins PhaP1, PhaP2, and PhaP4 are not substitutable without an impact on the amount of stored PHB. In particular, the phasins PhaP2 and PhaP4 seemed to limit the degradation of PHB by the PHB depolymerases PhaZ2, PhaZ3, and PhaZ7, whereas almost no influence of the different phasins was observed if phaZ1 was coexpressed. This study represents an extensive analysis of the impact of PHB depolymerases and phasins on PHB accumulation and provides a deeper insight into the complex interplay of these enzymes.
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Affiliation(s)
- Jessica Eggers
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms Universität Münster, Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms Universität Münster, Münster, Germany Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia
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To be or not to be a poly(3-hydroxybutyrate) (PHB) depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, highly active PHB depolymerases with no detectable role in mobilization of accumulated PHB. Appl Environ Microbiol 2014; 80:4936-46. [PMID: 24907326 DOI: 10.1128/aem.01056-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The putative physiological functions of two related intracellular poly(3-hydroxybutyrate) (PHB) depolymerases, PhaZd1 and PhaZd2, of Ralstonia eutropha H16 were investigated. Purified PhaZd1 and PhaZd2 were active with native PHB granules in vitro. Partial removal of the proteinaceous surface layer of native PHB granules by trypsin treatment or the use of PHB granules isolated from ΔphaP1 or ΔphaP1-phaP5 mutant strains resulted in increased specific PHB depolymerase activity, especially for PhaZd2. Constitutive expression of PhaZd1 or PhaZd2 reduced or even prevented the accumulation of PHB under PHB-permissive conditions in vivo. Expression of translational fusions of enhanced yellow fluorescent protein (EYFP) with PhaZd1 and PhaZd2 in which the active-site serines (S190 and Ser193) were replaced with alanine resulted in the colocalization of only PhaZd1 fusions with PHB granules. C-terminal fusions of inactive PhaZd2(S193A) with EYFP revealed the presence of spindle-like structures, and no colocalization with PHB granules was observed. Chromosomal deletion of phaZd1, phaZd2, or both depolymerase genes had no significant effect on PHB accumulation and mobilization during growth in nutrient broth (NB) or NB-gluconate medium. Moreover, neither proteome analysis of purified native PHB granules nor lacZ fusion studies gave any indication that PhaZd1 or PhaZd2 was detectably present in the PHB granule fraction or expressed at all during growth on NB-gluconate medium. In conclusion, PhaZd1 and PhaZd2 are two PHB depolymerases with a high capacity to degrade PHB when artificially expressed but are apparently not involved in PHB mobilization in the wild type. The true in vivo functions of PhaZd1 and PhaZd2 remain obscure.
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Jendrossek D, Pfeiffer D. New insights in the formation of polyhydroxyalkanoate granules (carbonosomes) and novel functions of poly(3-hydroxybutyrate). Environ Microbiol 2014; 16:2357-73. [PMID: 24329995 DOI: 10.1111/1462-2920.12356] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/27/2013] [Accepted: 12/05/2013] [Indexed: 12/18/2022]
Abstract
The metabolism of polyhydroxybutyrate (PHB) and related polyhydroxyalkanoates (PHAs) has been investigated by many groups for about three decades, and good progress was obtained in understanding the mechanisms of biosynthesis and biodegradation of this class of storage molecules. However, the molecular events that happen at the onset of PHB synthesis and the details of the initiation of PHB/PHA granule formation, as well as the complex composition of the proteinaceous surface layer of PHB/PHA granules, have only recently come into the focus of research and were not reviewed yet. In this contribution, we summarize the progress in understanding the initiation and formation of the PHA granule complex at the example of Ralstonia eutropha H16 (model organism of PHB-accumulating bacteria). Where appropriate, we include information on PHA granules of Pseudomonas putida as a representative species for medium-chain-length PHA-accumulating bacteria. We suggest to replace the previous micelle mode of PHB granule formation by the Scaffold Model in which the PHB synthase initiation complex is bound to the bacterial nucleoid. In the second part, we highlight data on other forms of PHB: oligo-PHB with ≈100 to 200 3-hydroxybutyrate (3HB) units and covalently bound PHB (cPHB) are unrelated in function to storage PHB but are presumably present in all living organisms, and therefore must be of fundamental importance.
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20
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3-Hydroxybutyrate oligomer hydrolase and 3-hydroxybutyrate dehydrogenase participate in intracellular polyhydroxybutyrate and polyhydroxyvalerate degradation in Paracoccus denitrificans. Appl Environ Microbiol 2013; 80:986-93. [PMID: 24271169 DOI: 10.1128/aem.03396-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genes encoding 3-hydroxybutyrate oligomer hydrolase (PhaZc) and 3-hydroxybutyrate dehydrogenase (Hbd) were isolated from Paracoccus denitrificans. PhaZc and Hbd were overproduced as His-tagged proteins in Escherichia coli and purified by affinity and gel filtration chromatography. Purified His-tagged proteins had molecular masses of 31 kDa and 120 kDa (a tetramer of 29-kDa subunits). The His-tagged PhaZc hydrolyzed not only 3-hydroxybutyrate oligomers but also 3-hydroxyvalerate oligomers. The His-tagged Hbd catalyzed the dehydrogenation of 3-hydroxyvalerate as well as 3-hydroxybutyrate. When both enzymes were included in the same enzymatic reaction system with 3-hydroxyvalerate dimer, sequential reactions occurred, suggesting that PhaZc and Hbd play an important role in the intracellular degradation of poly(3-hydroxyvalerate). When the phaZc gene was disrupted in P. denitrificans by insertional inactivation, the mutant strain lost PhaZc activity. When the phaZc-disrupted P. denitrificans was complemented with phaZc, PhaZc activity was restored. These results suggest that P. denitrificans carries a single phaZc gene. Disruption of the phaZc gene in P. denitrificans affected the degradation rate of PHA.
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21
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PhaM is the physiological activator of poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) in Ralstonia eutropha. Appl Environ Microbiol 2013; 80:555-63. [PMID: 24212577 DOI: 10.1128/aem.02935-13] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) is the key enzyme of PHB synthesis in Ralstonia eutropha and other PHB-accumulating bacteria and catalyzes the polymerization of 3-hydroxybutyryl-CoA to PHB. Activity assays of R. eutropha PHB 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 formation in vitro and in vivo was shown by cross-linking experiments of purified proteins (PhaM, PhaC1) with glutardialdehyde, by size exclusion chromatography, and by fluorescence microscopic detection of de novo-synthesized PHB granules.
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22
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Shiraki M, Okura H, Saito T. Transcriptional repression of the poly(3-hydroxybutyrate) depolymerase in Ralstonia pickettii T1 by a tetR-like gene. Antonie van Leeuwenhoek 2013; 105:89-98. [PMID: 24146107 DOI: 10.1007/s10482-013-0056-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/12/2013] [Indexed: 11/24/2022]
Abstract
Ralstonia pickettii T1 secretes a poly(3-hydroxybutyrate) (PHB) depolymerase (PhaZ) and a 3-hydroxybutyrate (3HB)-oligomer hydrolase, and extracellularly degrades PHB to produce 3HB. However, it is not clear how the expression of phaZ is regulated. In this study, the mechanism by which phaZ expression is controlled in R. pickettii T1 was examined using a mutant made by the random insertion of a transposon, Tn5. The mutant produced a larger amount of PhaZ than the wild type in nutrient broth or a minimal salt (SM) medium supplemented with succinate. However, there was essentially no difference in the activity or amount of PhaZ in the culture supernatant between the wild type and mutant when the two were grown on 3HB. The gene disrupted by the insertion of Tn5 (epdR) was cloned and its nucleotide sequence was determined. In a BLAST search, epdR showed a high degree of similarity to genes for TetR transcriptional regulators of several bacteria. The introduction of epdR into the wild type and mutant grown on the three media described above decreased the amount of PhaZ. These results indicated EpdR to be involved in the repression of phaZ in R. pickettii T1. A quantitative RT-PCR analysis indicated that mRNA levels corresponded with the activity detected and the amounts of PhaZ in the wild type and mutant. Furthermore, the amount of epdR transcript was inversely proportional to the amount of phaZ transcript. In addition, the existence of a positive element acting on phaZ expression was suggested, because in the mutant lacking EpdR, the amount of phaZ transcript varied in cells grown in SM-3HB, SM-succinate or nutrient broth. Based on the above results, a model for the regulation of PhaZ expression in R. pickettii T1 is proposed.
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Affiliation(s)
- Mari Shiraki
- Laboratory of Molecular Microbiology, Department of Biological Sciences, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
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23
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Madkour MH, Heinrich D, Alghamdi MA, Shabbaj II, Steinbüchel A. PHA Recovery from Biomass. Biomacromolecules 2013; 14:2963-72. [DOI: 10.1021/bm4010244] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohamed H. Madkour
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Daniel Heinrich
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Mansour A. Alghamdi
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Ibraheem I. Shabbaj
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Alexander Steinbüchel
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
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Eggers J, Steinbüchel A. Poly(3-hydroxybutyrate) degradation in Ralstonia eutropha H16 is mediated stereoselectively to (S)-3-hydroxybutyryl coenzyme A (CoA) via crotonyl-CoA. J Bacteriol 2013; 195:3213-23. [PMID: 23667237 PMCID: PMC3697646 DOI: 10.1128/jb.00358-13] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 05/07/2013] [Indexed: 11/20/2022] Open
Abstract
Degradation of poly(3-hydroxybutyrate) (PHB) by the thiolytic activity of the PHB depolymerase PhaZ1 from Ralstonia eutropha H16 was analyzed in the presence of different phasins. An Escherichia coli strain was constructed that harbored the genes for PHB synthesis (phaCAB), the phasin PhaP1, and the PHB depolymerase PhaZ1. PHB was isolated in the native form (nPHB) from this recombinant E. coli strain, and the in vitro degradation of the polyester was examined. Degradation resulted in the formation of the expected 3-hydroxybutyryl coenzyme A (3HB-CoA) and in the formation of a second product, which occurred in significantly higher concentrations than 3HB-CoA. This second product was identified by liquid chromatography mass spectrometry (LC-MS) as crotonyl-CoA. Replacement of PhaP1 by PhaP2 or PhaP4 resulted in a lower degradation rate, whereas the absence of the phasins prevented the degradation of nPHB by the PHB depolymerase PhaZ1 almost completely. In addition, the in vitro degradation of nPHB granules isolated from R. eutropha H16 (wild type) and from the R. eutropha ΔphaP1 and ΔphaP1-4 deletion mutants was examined. In contrast to the results obtained with nPHB granules isolated from E. coli, degradation of nPHB granules isolated from the wild type of R. eutropha yielded high concentrations of 3HB-CoA and low concentrations of crotonyl-CoA. The degradation of nPHB granules isolated from the ΔphaP1 and ΔphaP1-4 deletion mutants of R. eutropha was significantly reduced in comparison to that of nPHB granules isolated from wild-type R. eutropha. Stereochemical analyses of 3HB-CoA revealed that the (R) stereoisomer was collected after degradation of granules isolated from E. coli, whereas the (S) stereoisomer was collected after degradation of granules isolated from R. eutropha. Based on these results, a newly observed mechanism in the degradation pathway for PHB in R. eutropha is proposed which is connected by crotonyl-CoA to the β-oxidation cycle. According to this model, the NADPH-dependent synthesis of PHB with (R)-3HB-CoA as the intermediate and the PHB degradation yielding (S)-3HB-CoA, which is further converted in an NAD-dependent reaction, are separated.
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Affiliation(s)
- Jessica Eggers
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia
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25
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Simou OM, Pantazaki AA. Evidence for lytic transglycosylase and β-N-acetylglucosaminidase activities located at the polyhydroxyalkanoates (PHAs) granules of Thermus thermophilus HB8. Appl Microbiol Biotechnol 2013; 98:1205-21. [PMID: 23685478 DOI: 10.1007/s00253-013-4980-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 11/30/2022]
Abstract
The thermophilic bacterium Thermus thermophilus HB8 accumulates polyhydroxyalkanoates (PHAs) as intracellular granules used by cells as carbon and energy storage compounds. PHAs granules were isolated from cells grown in sodium gluconate (1.5 % w/v) as carbon source. Lytic activities are strongly associated and act to the PHAs granules proved with various methods. Specialized lytic trasglycosylases (LTGs) are muramidases capable of locally degrading the peptidoglycan (PG) meshwork of Gram negative bacteria. These enzymes cleave the β-1,4-glycosidic linkages between the N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) residues of PG. Lysozyme-like activity/-ies were detected using lysoplate assay. Chitinolytic activity/-ies, were detected as N-acetyl glucosaminidases (NAG) (E.C.3.2.1.5.52) hydrolyzing the synthetic substrate p-nitrophenyl-N-acetyl-β-D-glucosaminide (pNP-GlcNAc) releasing pNP and GlcNAc. Using zymogram analysis two abundant LTGs were revealed hydrolyzing cell wall of Micrococcus lysodeikticus or purified PG incorporated as natural substrates, in SDS-PAGE and then renaturation. These proteins corresponded in a SDS-PAGE and Coomassie-stained gel in molecular mass of 110 and 32 kDa respectively, were analyzed by MALDI-MS (Matrix-assisted laser desorption/ionization-Mass Spectrometry). The 110 kDa protein was identified as an S-layer domain-containing protein [gi|336233805], while the 32 kDa similar to the hypothetical protein VDG1235_2196 (gi/254443957). Overall, the localization of PG hydrolases in PHAs granules appears to be involved to their biogenesis from membranes, and probably promoting septal PG splitting and daughter cell separation.
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Affiliation(s)
- Olga M Simou
- Laboratory of Biochemistry, Dept. of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
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26
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Localization of poly(3-hydroxybutyrate) (PHB) granule-associated proteins during PHB granule formation and identification of two new phasins, PhaP6 and PhaP7, in Ralstonia eutropha H16. J Bacteriol 2012; 194:5909-21. [PMID: 22923598 DOI: 10.1128/jb.00779-12] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Poly(3-hydroxybutyrate) (PHB) granules are covered by a surface layer consisting of mainly phasins and other PHB granule-associated proteins (PGAPs). Phasins are small amphiphilic proteins that determine the number and size of accumulated PHB granules. Five phasin proteins (PhaP1 to PhaP5) are known for Ralstonia eutropha. In this study, we identified three additional potential phasin genes (H16_B1988, H16_B2296, and H16_B2326) by inspection of the R. eutropha genome for sequences with "phasin 2 motifs." To determine whether the corresponding proteins represent true PGAPs, fusions with eYFP (enhanced yellow fluorescent protein) were constructed. Similar fusions of eYFP with PhaP1 to PhaP5 as well as fusions with PHB synthase (PhaC1), an inactive PhaC1 variant (PhaC1-C319A), and PhaC2 were also made. All fusions were investigated in wild-type and PHB-negative backgrounds. Colocalization with PHB granules was found for all PhaC variants and for PhaP1 to PhaP5. Additionally, eYFP fusions with H16_B1988 and H16_B2326 colocalized with PHB. Fusions of H16_B2296 with eYFP, however, did not colocalize with PHB granules but did colocalize with the nucleoid region. Notably, all fusions (except H16_B2296) were soluble in a ΔphaC1 strain. These data confirm that H16_B1988 and H16_B2326 but not H16_B2296 encode true PGAPs, for which we propose the designation PhaP6 (H16_B1988) and PhaP7 (H16_B2326). When localization of phasins was investigated at different stages of PHB accumulation, fusions of PhaP6 and PhaP7 were soluble in the first 3 h under PHB-permissive conditions, although PHB granules appeared after 10 min. At later time points, the fusions colocalized with PHB. Remarkably, PHB granules of strains expressing eYFP fusions with PhaP5, PhaP6, or PhaP7 localized predominantly near the cell poles or in the area of future septum formation. This phenomenon was not observed for the other PGAPs (PhaP1 to PhaP4, PhaC1, PhaC1-C319A, and PhaC2) and indicated that some phasins can have additional functions. A chromosomal deletion of phaP6 or phaP7 had no visible effect on formation of PHB granules.
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Identification and biochemical evidence of a medium-chain-length polyhydroxyalkanoate depolymerase in the Bdellovibrio bacteriovorus predatory hydrolytic arsenal. Appl Environ Microbiol 2012; 78:6017-26. [PMID: 22706067 DOI: 10.1128/aem.01099-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The obligate predator Bdellovibrio bacteriovorus HD100 shows a large set of proteases and other hydrolases as part of its hydrolytic arsenal needed for its predatory life cycle. We present genetic and biochemical evidence that open reading frame (ORF) Bd3709 of B. bacteriovorus HD100 encodes a novel medium-chain-length polyhydroxyalkanoate (mcl-PHA) depolymerase (PhaZ(Bd)). The primary structure of PhaZ(Bd) suggests that this enzyme belongs to the α/β-hydrolase fold family and has a typical serine hydrolase catalytic triad (serine-histidine-aspartic acid) in agreement with other PHA depolymerases and lipases. PhaZ(Bd) has been extracellularly produced using different hypersecretor Tol-pal mutants of Escherichia coli and Pseudomonas putida as recombinant hosts. The recombinant PhaZ(Bd) has been characterized, and its biochemical properties have been compared to those of other PHA depolymerases. The enzyme behaves as a serine hydrolase that is inhibited by phenylmethylsulfonyl fluoride. It is also affected by the reducing agent dithiothreitol and nonionic detergents like Tween 80. PhaZ(Bd) is an endoexohydrolase that cleaves both large and small PHA molecules, producing mainly dimers but also monomers and trimers. The enzyme specifically degrades mcl-PHA and is inactive toward short-chain-length polyhydroxyalkanoates (scl-PHA) like polyhydroxybutyrate (PHB). These studies shed light on the potentiality of these predators as sources of new biocatalysts, such as an mcl-PHA depolymerase, for the production of enantiopure hydroxyalkanoic acids and oligomers as building blocks for the synthesis of biobased polymers.
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28
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Kaddor C, Voigt B, Hecker M, Steinbüchel A. Impact of the Core Components of the Phosphoenolpyruvate-Carbohydrate Phosphotransferase System, HPr and EI, on Differential Protein Expression in Ralstonia eutropha H16. J Proteome Res 2012; 11:3624-36. [DOI: 10.1021/pr300042f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Chlud Kaddor
- Institut für
Molekulare
Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse
3, D-48149 Münster, Germany
| | - Birgit Voigt
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Friedrich-Ludwig-Jahn-Straße
15, D-17489 Greifswald, Germany
| | - Michael Hecker
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Friedrich-Ludwig-Jahn-Straße
15, D-17489 Greifswald, Germany
| | - Alexander Steinbüchel
- Institut für
Molekulare
Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse
3, D-48149 Münster, Germany
- King Abdul Aziz University, Jeddah 22254,
Saudi Arabia
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29
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Cho M, Brigham CJ, Sinskey AJ, Stubbe J. Purification of polyhydroxybutyrate synthase from its native organism, Ralstonia eutropha: implications for the initiation and elongation of polymer formation in vivo. Biochemistry 2012; 51:2276-88. [PMID: 22369488 DOI: 10.1021/bi2013596] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Class I polyhydroxybutyrate (PHB) synthase (PhaC) from Ralstonia eutropha catalyzes the formation of PHB from (R)-3-hydroxybutyryl-CoA, ultimately resulting in the formation of insoluble granules. Previous mechanistic studies of R. eutropha PhaC, purified from Escherichia coli (PhaC(Ec)), demonstrated that the polymer elongation rate is much faster than the initiation rate. In an effort to identify a factor(s) from the native organism that might prime the synthase and increase the rate of polymer initiation, an N-terminally Strep2-tagged phaC (Strep2-PhaC(Re)) was constructed and integrated into the R. eutropha genome in place of wild-type phaC. Strep2-PhaC(Re) was expressed and purified by affinity chromatography from R. eutropha grown in nutrient-rich TSB medium for 4 h (peak production PHB, 15% cell dry weight) and 24 h (PHB, 2% cell dry weight). Analysis of the purified PhaC by size exclusion chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and gel permeation chromatography revealed that it unexpectedly copurified with the phasin protein, PhaP1, and with soluble PHB (M(w) = 350 kDa) in a "high-molecular weight" (HMW) complex and in monomeric/dimeric (M/D) forms with no associated PhaP1 or PHB. Assays for monitoring the formation of PHB in the HMW complex showed no lag phase in CoA release, in contrast to M/D forms of PhaC(Re) (and PhaC(Ec)), suggesting that PhaC in the HMW fraction has been isolated in a PHB-primed form. The presence of primed and nonprimed PhaC suggests that the elongation rate for PHB formation is also faster than the initiation rate in vivo. A modified micelle model for granule genesis is proposed to accommodate the reported observations.
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Affiliation(s)
- Mimi Cho
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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30
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Brandt U, Raberg M, Voigt B, Hecker M, Steinbüchel A. Elevated poly(3-hydroxybutyrate) synthesis in mutants of Ralstonia eutropha H16 defective in lipopolysaccharide biosynthesis. Appl Microbiol Biotechnol 2012; 95:471-83. [DOI: 10.1007/s00253-012-3909-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/11/2012] [Accepted: 01/17/2012] [Indexed: 11/24/2022]
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31
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Growth and localization of polyhydroxybutyrate granules in Ralstonia eutropha. J Bacteriol 2011; 194:1092-9. [PMID: 22178974 DOI: 10.1128/jb.06125-11] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The bacterium Ralstonia eutropha forms cytoplasmic granules of polyhydroxybutyrate that are a source of biodegradable thermoplastic. While much is known about the biochemistry of polyhydroxybutyrate production, the cell biology of granule formation and growth remains unclear. Previous studies have suggested that granules form either in the inner membrane, on a central scaffold, or in the cytoplasm. Here we used electron cryotomography to monitor granule genesis and development in 3 dimensions (3-D) in a near-native, "frozen-hydrated" state in intact Ralstonia eutropha cells. Neither nascent granules within the cell membrane nor scaffolds were seen. Instead, granules of all sizes resided toward the center of the cytoplasm along the length of the cell and exhibited a discontinuous surface layer more consistent with a partial protein coating than either a lipid mono- or bilayer. Putatively fusing granules were also seen, suggesting that small granules are continually generated and then grow and merge. Together, these observations support a model of biogenesis wherein granules form in the cytoplasm coated not by phospholipid but by protein. Previous thin-section electron microscopy (EM), fluorescence microscopy, and atomic force microscopy (AFM) results to the contrary may reflect both differences in nucleoid condensation and specimen preparation-induced artifacts.
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32
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Pfeiffer D, Wahl A, Jendrossek D. Identification of a multifunctional protein, PhaM, that determines number, surface to volume ratio, subcellular localization and distribution to daughter cells of poly(3-hydroxybutyrate), PHB, granules in Ralstonia eutropha H16. Mol Microbiol 2011; 82:936-51. [DOI: 10.1111/j.1365-2958.2011.07869.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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33
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Pfeiffer D, Jendrossek D. Interaction between poly(3-hydroxybutyrate) granule-associated proteins as revealed by two-hybrid analysis and identification of a new phasin in Ralstonia eutropha H16. Microbiology (Reading) 2011; 157:2795-2807. [DOI: 10.1099/mic.0.051508-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A large number of polypeptides are attached to poly(3-hydroxybutyrate) (PHB) granules of Ralstonia eutropha, such as PHB synthase (PhaC1), several PHB depolymerases (PhaZs) and phasins (PhaPs), the regulator protein PhaR
Reu
, and possibly others. In this study we used the bacterial adenylate cyclase-based two-hybrid assay to investigate interactions between known PHB granule-associated proteins (PGAPs) and to screen for new PGAPs. The utility of the system was tested by the in vivo verification of previously postulated interactions of the PHB synthase subunits of R. eutropha (PhaC1 homo-oligomerization) and of Bacillus megaterium (PhaC
Bmeg
–PhaR
Bmeg
hetero-oligomerization). Nine proteins (PhaA, PhaB1, PhaC1, PhaP1–PhaP4, PhaZ1 and PhaR), with established functions in PHB metabolism of R. eutropha, were tested for interaction in all combinations. While no significant interaction was detected between the PHB synthase PhaC1 and any of the other eight tested Pha proteins, strong interactions were found between all phasin proteins, in particular between PhaP2 and PhaP4. When PhaP2 was used as bait in a two-hybrid screening experiment with a genomic library of R. eutropha, the B1934 gene product was identified in 24 out of 53 isolated clones. B1934 encodes a hypothetical protein (15.7 kDa) with similarity to phasins of PHB-accumulating bacteria. A fusion protein of eYfp and the B1934 gene product colocalized with PHB granules, confirming that B1934 represents a new phasin (PhaP5). PhaP5 was not essential for PHB granule formation, but overexpression of PhaP5 increased the number of cells with PHB granules at the cell poles.
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Affiliation(s)
- Daniel Pfeiffer
- Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, Stuttgart, Germany
| | - Dieter Jendrossek
- Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, Stuttgart, Germany
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Versatile metabolic adaptations of Ralstonia eutropha H16 to a loss of PdhL, the E3 component of the pyruvate dehydrogenase complex. Appl Environ Microbiol 2011; 77:2254-63. [PMID: 21296938 DOI: 10.1128/aem.02360-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previous study reported that the Tn5-induced poly(3-hydroxybutyric acid) (PHB)-leaky mutant Ralstonia eutropha H1482 showed a reduced PHB synthesis rate and significantly lower dihydrolipoamide dehydrogenase (DHLDH) activity than the wild-type R. eutropha H16 but similar growth behavior. Insertion of Tn5 was localized in the pdhL gene encoding the DHLDH (E3 component) of the pyruvate dehydrogenase complex (PDHC). Taking advantage of the available genome sequence of R. eutropha H16, observations were verified and further detailed analyses and experiments were done. In silico genome analysis revealed that R. eutropha possesses all five known types of 2-oxoacid multienzyme complexes and five DHLDH-coding genes. Of these DHLDHs, only PdhL harbors an amino-terminal lipoyl domain. Furthermore, insertion of Tn5 in pdhL of mutant H1482 disrupted the carboxy-terminal dimerization domain, thereby causing synthesis of a truncated PdhL lacking this essential region, obviously leading to an inactive enzyme. The defined ΔpdhL deletion mutant of R. eutropha exhibited the same phenotype as the Tn5 mutant H1482; this excludes polar effects as the cause of the phenotype of the Tn5 mutant H1482. However, insertion of Tn5 or deletion of pdhL decreases DHLDH activity, probably negatively affecting PDHC activity, causing the mutant phenotype. Moreover, complementation experiments showed that different plasmid-encoded E3 components of R. eutropha H16 or of other bacteria, like Burkholderia cepacia, were able to restore the wild-type phenotype at least partially. Interestingly, the E3 component of B. cepacia possesses an amino-terminal lipoyl domain, like the wild-type H16. A comparison of the proteomes of the wild-type H16 and of the mutant H1482 revealed striking differences and allowed us to reconstruct at least partially the impressive adaptations of R. eutropha H1482 to the loss of PdhL on the cellular level.
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Peplinski K, Ehrenreich A, Döring C, Bömeke M, Steinbüchel A. Investigations on the microbial catabolism of the organic sulfur compounds TDP and DTDP in Ralstonia eutropha H16 employing DNA microarrays. Appl Microbiol Biotechnol 2010; 88:1145-59. [PMID: 20924576 PMCID: PMC3128720 DOI: 10.1007/s00253-010-2915-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 09/05/2010] [Accepted: 09/08/2010] [Indexed: 11/27/2022]
Abstract
In this study, we have investigated the transcriptome of Ralstonia eutropha H16 during cultivation with gluconate in presence of 3,3′-thiodipropionic acid (TDP) or 3,3′-dithiodipropionic acid (DTDP) during biosynthesis of poly(3-hydroxybutyrate-co-3-mercaptopropionate). Genome-wide transcriptome analyses revealed several genes which were upregulated during cultivation in presence of the above-mentioned compounds. Obtained data strongly suggest that two ABC-type transport system and three probable extracytoplasmic solute receptors mediate the uptake of TDP and DTDP, respectively. In addition, genes encoding the hydrolase S-adenosylhomocysteinase AhcY and the thiol-disulfide interchange proteins DsbA, DsbD, and FrnE were upregulated during cultivation on DTDP and, in case of AhcY and FrnE, on TDP as well. It is assumed that the corresponding enzymes are involved in the cleavage of TDP and DTDP. Several genes of the fatty acid metabolism exhibited increased expression levels: genes encoding two acetyltransferases, a predicted acyltransferase, the acetoacetyl-CoA reductase phaB3, an enoyl-CoA hydratase as well as an acyl dehydratase, an acetyl-CoA synthetase, two acyl-CoA dehydrogenases, the methylmalonyl-CoA mutase encoded by sbm1 and sbm2 and phaY1 were detected. Furthermore, ORF H16_A0217 encoding a hypothetical protein and exhibiting 54% amino acids identical to an acyl-CoA thioesterase from Saccharomonospora viridis was found to be highly upregulated. As the 2-methylcitrate synthase PrpC exhibited a three- to fourfold increased activity in cells grown in presence of TDP or DTDP as compared to gluconate, metabolization of the cleavage products 3MP and 3-hydroxypropionate to propionyl-CoA is proposed.
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Affiliation(s)
- Katja Peplinski
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, 48149 Münster, Germany
| | - Armin Ehrenreich
- Institut für Mikrobiologie, Technische Universität München, Am Hochanger 4, 85354 Freising, Germany
| | - Christina Döring
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Mechthild Bömeke
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, 48149 Münster, Germany
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Povolo S, Toffano P, Basaglia M, Casella S. Polyhydroxyalkanoates production by engineered Cupriavidus necator from waste material containing lactose. BIORESOURCE TECHNOLOGY 2010; 101:7902-7907. [PMID: 20537531 DOI: 10.1016/j.biortech.2010.05.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 05/06/2010] [Accepted: 05/10/2010] [Indexed: 05/29/2023]
Abstract
Cupriavidus necator DSM 545 is a well-known polyhydroxyalkanoates (PHAs) producer, but unable to grow on lactose. The aim of this study was to construct a recombinant strain of C. necator that can use lactose-containing waste material such as cheese whey, to produce PHAs. One of the intracellular PHA depolymerases (phaZ1) of C. necator was chosen to insert the lacZ, lacI and lacO genes of Escherichia coli. This would have the effect to allow polymer production on lactose and, at the same time, to remove part of the PHA intracellular degradation system. Disruption of phaZ1 was achieved by gene replacement after isolating a fragment of this gene and interrupting it with a cartridge containing the lac genes and a synthetic promoter. Growth and polymer production studies of the genetically modified (GM) strain mRePT in lactose, whey permeate and hydrolyzed whey permeate as carbon sources, were performed. Lower PHA degradation and higher yields were obtained compared to the wild-type strain. Inactivation of the putative depolymerase gene phaZ3 on mRePT recombinant strain was also reported.
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Affiliation(s)
- Silvana Povolo
- Dipartimento di Biotecnologie Agrarie, Università di Padova, Viale dell'Università 16, 35020 Legnaro Padova, Italy
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Roles of multiple acetoacetyl coenzyme A reductases in polyhydroxybutyrate biosynthesis in Ralstonia eutropha H16. J Bacteriol 2010; 192:5319-28. [PMID: 20729355 DOI: 10.1128/jb.00207-10] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterium Ralstonia eutropha H16 synthesizes polyhydroxybutyrate (PHB) from acetyl coenzyme A (acetyl-CoA) through reactions catalyzed by a β-ketothiolase (PhaA), an acetoacetyl-CoA reductase (PhaB), and a polyhydroxyalkanoate synthase (PhaC). An operon of three genes encoding these enzymatic steps was discovered in R. eutropha and has been well studied. Sequencing and analysis of the R. eutropha genome revealed putative isologs for each of the PHB biosynthetic genes, many of which had never been characterized. In addition to the previously identified phaB1 gene, the genome contains the isologs phaB2 and phaB3 as well as 15 other potential acetoacetyl-CoA reductases. We have investigated the roles of the three phaB isologs by deleting them from the genome individually and in combination. It was discovered that the gene products of both phaB1 and phaB3 contribute to PHB biosynthesis in fructose minimal medium but that in plant oil minimal medium and rich medium, phaB3 seems to be unexpressed. This raises interesting questions concerning the regulation of phaB3 expression. Deletion of the gene phaB2 did not result in an observable phenotype under the conditions tested, although this gene does encode an active reductase. Addition of the individual reductase genes to the genome of the ΔphaB1 ΔphaB2 ΔphaB3 strain restored PHB production, and in the course of our complementation experiments, we serendipitously created a PHB-hyperproducing mutant. Measurement of the PhaB and PhaA activities of the mutant strains indicated that the thiolase reaction is the limiting step in PHB biosynthesis in R. eutropha H16 during nitrogen-limited growth on fructose.
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Peplinski K, Ehrenreich A, Döring C, Bömeke M, Reinecke F, Hutmacher C, Steinbüchel A. Genome-wide transcriptome analyses of the ‘Knallgas’ bacterium Ralstonia eutropha H16 with regard to polyhydroxyalkanoate metabolism. Microbiology (Reading) 2010; 156:2136-2152. [DOI: 10.1099/mic.0.038380-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
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 ΔphaC1 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 ΔphaC1 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 wild-type, and phaP1, phaP4, phaZ2 and phaZ6 exhibited an elevated transcription level in PHB−4. In strain ΔphaC1, 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 H16ΔphaC1, no PHA production was observed. PhaC2 activity could not be detected in any experiment.
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Affiliation(s)
- Katja Peplinski
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149 Münster, Germany
| | - Armin Ehrenreich
- Institut für Mikrobiologie, Technische Universität München, Am Hochanger 4, D85354 Freising, Germany
| | - Christina Döring
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Mechthild Bömeke
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Frank Reinecke
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149 Münster, Germany
| | - Carmen Hutmacher
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149 Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149 Münster, Germany
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Trainer MA, Capstick D, Zachertowska A, Lam KN, Clark SRD, Charles TC. Identification and characterization of the intracellular poly-3-hydroxybutyrate depolymerase enzyme PhaZ of Sinorhizobium meliloti. BMC Microbiol 2010; 10:92. [PMID: 20346169 PMCID: PMC2867953 DOI: 10.1186/1471-2180-10-92] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Accepted: 03/27/2010] [Indexed: 11/23/2022] Open
Abstract
Background S. meliloti forms indeterminate nodules on the roots of its host plant alfalfa (Medicago sativa). Bacteroids of indeterminate nodules are terminally differentiated and, unlike their non-terminally differentiated counterparts in determinate nodules, do not accumulate large quantities of Poly-3-hydroxybutyrate (PHB) during symbiosis. PhaZ is in intracellular PHB depolymerase; it represents the first enzyme in the degradative arm of the PHB cycle in S. meliloti and is the only enzyme in this half of the PHB cycle that remains uncharacterized. Results The S. meliloti phaZ gene was identified by in silico analysis, the ORF was cloned, and a S. meliloti phaZ mutant was constructed. This mutant exhibited increased PHB accumulation during free-living growth, even when grown under non-PHB-inducing conditions. The phaZ mutant demonstrated no reduction in symbiotic capacity; interestingly, analysis of the bacteroids showed that this mutant also accumulated PHB during symbiosis. This mutant also exhibited a decreased capacity to tolerate long-term carbon starvation, comparable to that of other PHB cycle mutants. In contrast to other PHB cycle mutants, the S. meliloti phaZ mutant did not exhibit any decrease in rhizosphere competitiveness; however, this mutant did exhibit a significant increase in succinoglycan biosynthesis. Conclusions S. meliloti bacteroids retain the capacity to synthesize PHB during symbiosis; interestingly, accumulation does not occur at the expense of symbiotic performance. phaZ mutants are not compromised in their capacity to compete for nodulation in the rhizosphere, perhaps due to increased succinoglycan production resulting from upregulation of the succinoglycan biosynthetic pathway. The reduced survival capacity of free-living cells unable to access their accumulated stores of PHB suggests that PHB is a crucial metabolite under adverse conditions.
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Affiliation(s)
- Maria A Trainer
- Department of Biology, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
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Chou ME, Yang MK. Analyses of binding sequences of the PhaR protein of Rhodobacter sphaeroides FJ1. FEMS Microbiol Lett 2009; 302:138-43. [PMID: 19925635 DOI: 10.1111/j.1574-6968.2009.01836.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The phaC, phaP, phaR, and phaZ genes are involved in the synthesis, accumulation, and degradation of poly-beta-hydroxybutyrate (PHB). These genes encode the PHB synthase, phasin, regulatory protein, and PHB depolymerase, respectively, and are located in the same locus in the genome of Rhodobacter sphaeroides FJ1, a purple nonsulfur bacterium capable of producing PHB. We have previously found that the PhaR protein binds to the promoter regions of phaP, phaR, and phaZ and represses their expression. In this study, we determined that PhaR binds to an 11-bp palindromic sequence, 5'-CTGCN(3)GCAG-3', located at nucleotides -69 to -59 and -97 to -87 relative to the translation start site of phaP. Substitution of the three spacer nucleotides with any three or four nucleotides in this sequence had no effect on PhaR binding, but all other base deletions or substitutions in this sequence abolished its ability to bind PhaR both in vitro and in vivo. These results suggest that PhaR regulates the expression of phaP in R. sphaeroides FJ1.
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Affiliation(s)
- Min-En Chou
- Graduate Institute of Applied Science and Engineering, Fu Jen University, Taipei, Taiwan, Republic of China
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Complete PHB mobilization in Escherichia coli enhances the stress tolerance: a potential biotechnological application. Microb Cell Fact 2009; 8:47. [PMID: 19719845 PMCID: PMC2746179 DOI: 10.1186/1475-2859-8-47] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 08/31/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Poly-beta-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions. Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria. RESULTS The successful expression of PHB biosynthesis and PHB depolymerase genes in E. coli was confirmed by PHB production and 3-hydroxybutyrate secretion. Starvation experiment demonstrated that the complete PHB mobilization system in E. coli served as an intracellular energy and carbon storage system, which increased the survival rate of the host when carbon resources were limited. Stress tolerance experiment indicated that E. coli strains with PHB production and mobilization system exhibited an enhanced stress resistance capability. CONCLUSION This engineered E. coli with PHB mobilization has a potential biotechnological application as immobilized cell factories for biocatalysis and biotransformation.
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Identification and characterization of a novel intracellular poly(3-hydroxybutyrate) depolymerase from Bacillus megaterium. Appl Environ Microbiol 2009; 75:5290-9. [PMID: 19561190 DOI: 10.1128/aem.00621-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A gene that codes for a novel intracellular poly(3-hydroxybutyrate) (PHB) depolymerase, designated PhaZ1, has been identified in the genome of Bacillus megaterium. A native PHB (nPHB) granule-binding assay showed that purified soluble PhaZ1 had strong affinity for nPHB granules. Turbidimetric analyses revealed that PhaZ1 could rapidly degrade nPHB granules in vitro without the need for protease pretreatment of the granules to remove surface proteins. Notably, almost all the final hydrolytic products produced from the in vitro degradation of nPHB granules by PhaZ1 were 3-hydroxybutyric acid (3HB) monomers. Unexpectedly, PhaZ1 could also hydrolyze denatured semicrystalline PHB, with the generation of 3HB monomers. The disruption of the phaZ1 gene significantly affected intracellular PHB mobilization during the PHB-degrading stage in B. megaterium, as demonstrated by transmission electron microscopy and the measurement of the PHB content. These results indicate that PhaZ1 is functional in intracellular PHB mobilization in vivo. Some of these features, which are in striking contrast with those of other known nPHB granule-degrading PhaZs, may provide an advantage for B. megaterium PhaZ1 in fermentative production of the biotechnologically valuable chiral compound (R)-3HB.
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Chou ME, Chang WT, Chang YC, Yang MK. Expression of four pha genes involved in poly-beta-hydroxybutyrate production and accumulation in Rhodobacter sphaeroides FJ1. Mol Genet Genomics 2009; 282:97-106. [PMID: 19404680 DOI: 10.1007/s00438-009-0448-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 04/14/2009] [Indexed: 10/20/2022]
Abstract
A cluster of genes encoding polyhydroxybutyrate (PHB) depolymerase (phaZ), PHB synthase (phaC), phasin (phaP), and the regulator protein (phaR) was previously identified in Rhodobacter sphaeroides FJ1 (R. sphaeroides FJ1). In this study, we investigated the role of the PhaR protein on the expression of the pha genes. Immunoblot analysis revealed that the expressions of phaP, phaZ and phaR genes in wild-type cells of R. sphaeroides FJ1 are repressed during the active growth phase, with the exception of phaC. A phaR deletion mutant of R. sphaeroides FJ1 was constructed, and the basal level of phaP and phaZ expression in this mutant was markedly increased. Electrophoretic mobility shift assays demonstrated that PhaR binds to the promoter region of phaP as well as those of phaR and phaZ. These results suggest that the PhaR protein is a repressor of phaP, phaR, and phaZ genes in R. sphaeroides FJ1.
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Affiliation(s)
- Min-En Chou
- Graduate Institute of Applied Science and Engineering, Fu Jen University, Taipei, Taiwan, Republic of China.
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Knoll M, Hamm TM, Wagner F, Martinez V, Pleiss J. The PHA Depolymerase Engineering Database: A systematic analysis tool for the diverse family of polyhydroxyalkanoate (PHA) depolymerases. BMC Bioinformatics 2009; 10:89. [PMID: 19296857 PMCID: PMC2666664 DOI: 10.1186/1471-2105-10-89] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 03/18/2009] [Indexed: 01/16/2023] Open
Abstract
Background Polyhydroxyalkanoates (PHAs) can be degraded by many microorganisms using intra- or extracellular PHA depolymerases. PHA depolymerases are very diverse in sequence and substrate specificity, but share a common α/β-hydrolase fold and a catalytic triad, which is also found in other α/β-hydrolases. Results The PHA Depolymerase Engineering Database (DED, ) has been established as a tool for systematic analysis of this enzyme family. The DED contains sequence entries of 587 PHA depolymerases, which were assigned to 8 superfamilies and 38 homologous families based on their sequence similarity. For each family, multiple sequence alignments and profile hidden Markov models are provided, and functionally relevant residues are annotated. Conclusion The DED is a valuable tool which can be applied to identify new PHA depolymerase sequences from complete genomes in silico, to classify PHA depolymerases, to predict their biochemical properties, and to design enzyme variants with improved properties.
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Affiliation(s)
- Michael Knoll
- Institute of Technical Biochemistry, University of Stuttgart, Allmandring, Germany.
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Grage K, Jahns AC, Parlane N, Palanisamy R, Rasiah IA, Atwood JA, Rehm BHA. Bacterial Polyhydroxyalkanoate Granules: Biogenesis, Structure, and Potential Use as Nano-/Micro-Beads in Biotechnological and Biomedical Applications. Biomacromolecules 2009; 10:660-9. [DOI: 10.1021/bm801394s] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katrin Grage
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Anika C. Jahns
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Natalie Parlane
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Rajasekaran Palanisamy
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Indira A. Rasiah
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Jane A. Atwood
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Bernd H. A. Rehm
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand and Hopkirk Research Institute, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
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Polyhydroxyalkanoate granules are complex subcellular organelles (carbonosomes). J Bacteriol 2009; 191:3195-202. [PMID: 19270094 DOI: 10.1128/jb.01723-08] [Citation(s) in RCA: 228] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Accumulation of Intracellular Polyhydroxybutyrate in Alcaligenes sp. d2 Under Phenol Stress. Appl Biochem Biotechnol 2008; 159:545-52. [DOI: 10.1007/s12010-008-8454-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2008] [Accepted: 11/25/2008] [Indexed: 10/21/2022]
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Kadouri D, Jurkevitch E, Okon Y, Castro-Sowinski S. Ecological and Agricultural Significance of Bacterial Polyhydroxyalkanoates. Crit Rev Microbiol 2008; 31:55-67. [PMID: 15986831 DOI: 10.1080/10408410590899228] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Polyhydroxyalkanoates (PHAs) are a group of carbon andenergy storage compounds that are accumulated during suboptimal growth by many bacteria, and intracellularly deposited in the form of inclusion bodies. Accumulation of PHAs is thought to be used by bacteria to increase survival and stress tolerance in changing environments, and in competitive settings where carbon and energy sources may be limited, such as those encountered in the soil and the rhizosphere. Understanding the role that PHAs play as internal storage polymers is of fundamental importance in microbial ecology, and holds great potential for the improvement of bacterial inoculants for plants and soils. This review summarizes the current knowledge on the ecological function of PHAs, and their strategic role as survival factors in microorganisms under varying environmental stress is emphasized. It also explores the phylogeny of the PHA cycle enzymes, PHA synthase, and PHA depolymerase, suggesting that PHA accumulation was earlier acquired and maintained during evolution, thus contributing to microbial survival in the environment.
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Affiliation(s)
- Daniel Kadouri
- Department of Plant Pathology and Microbiology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
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Raberg M, Reinecke F, Reichelt R, Malkus U, König S, Pötter M, Fricke WF, Pohlmann A, Voigt B, Hecker M, Friedrich B, Bowien B, Steinbüchel A. Ralstonia eutropha H16 flagellation changes according to nutrient supply and state of poly(3-hydroxybutyrate) accumulation. Appl Environ Microbiol 2008; 74:4477-90. [PMID: 18502919 PMCID: PMC2493158 DOI: 10.1128/aem.00440-08] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 05/10/2008] [Indexed: 11/20/2022] Open
Abstract
Two-dimensional polyacrylamide gel electrophoresis (2D PAGE), in combination with matrix-assisted laser desorption ionization-time of flight analysis, and the recently revealed genome sequence of Ralstonia eutropha H16 were employed to detect and identify proteins that are differentially expressed during different phases of poly(3-hydroxybutyric acid) (PHB) metabolism. For this, a modified protein extraction protocol applicable to PHB-harboring cells was developed to enable 2D PAGE-based proteome analysis of such cells. Subsequently, samples from (i) the exponential growth phase, (ii) the stationary growth phase permissive for PHB biosynthesis, and (iii) a phase permissive for PHB mobilization were analyzed. Among several proteins exhibiting quantitative changes during the time course of a cultivation experiment, flagellin, which is the main protein of bacterial flagella, was identified. Initial investigations that report on changes of flagellation for R. eutropha were done, but 2D PAGE and electron microscopic examinations of cells revealed clear evidence that R. eutropha exhibited further significant changes in flagellation depending on the life cycle, nutritional supply, and, in particular, PHB metabolism. The results of our study suggest that R. eutropha is strongly flagellated in the exponential growth phase and loses a certain number of flagella in transition to the stationary phase. In the stationary phase under conditions permissive for PHB biosynthesis, flagellation of cells admittedly stagnated. However, under conditions permissive for intracellular PHB mobilization after a nitrogen source was added to cells that are carbon deprived but with full PHB accumulation, flagella are lost. This might be due to a degradation of flagella; at least, the cells stopped flagellin synthesis while normal degradation continued. In contrast, under nutrient limitation or the loss of phasins, cells retained their flagella.
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Affiliation(s)
- Matthias Raberg
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany
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