Biosynthesis of poly-(R)-3-hydroxyalkanoate: An emulsion polymerization

Koning, de Gjm Gertjan; Maxwell, Ian

doi:10.1007/bf01458030

Cited by 27 publications

(12 citation statements)

References 26 publications

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“…PHA inclusions appear to have a single boundary layer, which was first believed to be a membrane 15 to 20 nm in thickness or a homogenous layer of PhaC (42,88,92). Later reports described the inclusions to be surrounded by a PL monolayer with a 4-nm width and with proteins engaged in PHA synthesis, mobilization, and structural function embedded (38,61,93). In R. eutropha, four classes of proteins have been demonstrated to occur at the surface of PHA inclusions: PhaC; PhaZ; a transcriptional repressor, PhaR; and phasins (PhaP).…”

Section: Vol 187 2005mentioning

confidence: 99%

Neutral Lipid Bodies in Prokaryotes: Recent Insights into Structure, Formation, and Relationship to Eukaryotic Lipid Depots

2005

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Many prokaryotes are able to accumulate large amounts of lipophilic compounds as inclusion bodies in the cytoplasm. Members of most genera synthesize polymeric lipids such as poly(3-hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHAs) (125), whereas accumulation of triacylglycerols (TAGs) and wax esters (WEs) in intracellular lipid-bodies is a property of only a few prokaryotes (10). Like the formation of PHAs, TAG and WE biosynthesis is also promoted in response to stress imposed on the cells and during imbalanced growth, for example by nitrogen limitation, if an abundant carbon source is present at the same time. All these lipids act as storage compounds for energy and carbon needed for maintenance of metabolism and synthesis of cellular metabolites during starvation and in particular if growth resumes. Although neutral lipid metabolism in bacteria, especially WE biosynthesis, has attracted increasing biotechnological interest, there has so far been little interest in medical research in the formation of prokaryotic lipid bodies. However, recent findings suggest that lipid body formation and accumulation of TAGs play an important role in the metabolism of the pathogenic bacteria like Mycobacterium tuberculosis (37,52).In contrast to the restricted occurrence of storage TAGs in prokaryotes, intracellular TAGs are widespread in many eukaryotes (34,35,40,53,65,106,112,132,133). In eukaryotes, storage lipids are also deposited as lipid bodies. Their structure and formation have recently been reviewed in detail by several authors, but additional information on prokaryotic lipid-bodies has been only superficial (98,100,151). In contrast, intracellular accumulation of WEs as a storage lipid is a great exception in eukaryotes and occurs only in jojoba (Simmondsia chinensis) (147), and PHAs are not at all synthesized as a storage compound in eukaryotes.The number of studies investigating the enzymatic and structural fundamentals of storage lipid metabolism in bacteria has increased drastically in the last years, providing the knowledge that storage lipids in bacteria have a similar important metabolic function like in eukaryotes. This review will focus on prokaryotic neutral lipid bodies in comparison with the currently discussed models for lipid body structure and their formation in eukaryotes and with PHA inclusions in prokaryotes.

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Section: Vol 187 2005mentioning

confidence: 99%

Neutral Lipid Bodies in Prokaryotes: Recent Insights into Structure, Formation, and Relationship to Eukaryotic Lipid Depots

2005

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“…Recently, it has been suggested that this simply results from the slow nucleation kinetics of small PHA par- NARD andSANDERS, 1988, 1989; KAWAGU-ticles. For a typical poly(3HB) granule exhibiting a diameter of 0.5 mm, the time to nucleate for crystallization is approximately 30,000 years (DE KONING and MAXWELL, 1993). A much shorter crystallization period can be induced by compaction of the granules by centrifugation, perturbation by sonication, damage of the surrounding membrane by exposure of the granules to solvents, sodium hydrochlorite or to hydrolytic enzymes, or by freezing and thawing cycles (BARNARD and SANDERS, 1989;DE KONING and MAXWELL, 1993).…”

Section: Function Of Phamentioning

confidence: 99%

PHB and Other Polhydroxyalkanoic Acids

Steinbüchel¹

1996

Biotechnology

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“…eutropha H16 has not yet been identified. However, PHB granules, as well as TAG inclusions, possess a hydrophobic core of the polyester or lipid, respectively, which is thought to be surrounded by a monolayer of phospholipids (de Koning & Maxwell, 1993;Hocking & Marchessault, 1994;Mayer & Hoppert, 1997;Wältermann et al, 2005). This common structure allows the targeting of PhaP1 to PHB granules and also TAG inclusions, as demonstrated in this study.…”

Section: Discussionmentioning

confidence: 99%

The Ralstonia eutropha H16 phasin PhaP1 is targeted to intracellular triacylglycerol inclusions in Rhodococcus opacus PD630 and Mycobacterium smegmatis mc2155, and provides an anchor to target other proteins

et al. 2006

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The Ralstonia eutropha H16 phasin PhaP1 is targeted to intracellular triacylglycerol inclusions in Rhodococcus opacus PD630 and Mycobacterium smegmatis mc 2 155, and provides an anchor to target other proteins In Ralstonia eutropha, the H16 phasin PhaP1 represents the major phasin that binds to the surface of polyhydroxyalkanoate (PHA) inclusions. In this study, C-terminal fusions of PhaP1 with enhanced green fluorescent protein (eGFP) and with Escherichia coli b-galactosidase (LacZ) were expressed separately in the triacylglycerol (TAG)-accumulating actinomycetes Rhodococcus opacus PD630 and Mycobacterium smegmatis mc 2 155, employing the M. smegmatis acetamidase (ace) promoter of the Escherichia-Mycobacterium/Rhodococcus shuttle plasmid pJAM2. PhaP1 and the PhaP1 fusion proteins were expressed stably in the recombinant strains. Western blot analysis of cell fractions of Rh. opacus revealed that PhaP1 and the PhaP1-eGFP fusion protein were associated with the TAG inclusions, whereas no phasin or phasin fusion protein was detected in the soluble and membrane fractions. Additional electron microscopy/ immunocytochemistry studies demonstrated that PhaP1 was mainly located on the surface of intracellular TAG inclusions; in addition, some PhaP1 also occurred at the plasma membrane. Fluorescence microscopic investigations of the subcellular distribution of the PhaP1-eGFP fusion protein in vivo and on isolated TAG inclusions revealed that the fusion protein was bound to TAG inclusions at all stages of their formation, and to some extent at the cytoplasmic membrane. The PhaP1-LacZ fusion protein also bound to the TAG inclusions, and could be separated together with the inclusions from Rh. opacus crude extracts, thus demonstrating the immobilization of b-galactosidase activity on the inclusions. This is believed to be the first report demonstrating the ability of PhaP1 to bind to lipid inclusions in addition to PHA inclusions. Furthermore, it was demonstrated that this non-specificity of PhaP1 can be utilized to anchor enzymically active fusion proteins to a matrix of bacterial TAG inclusions.

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Biosynthesis of poly-(R)-3-hydroxyalkanoate: An emulsion polymerization

Cited by 27 publications

References 26 publications

Neutral Lipid Bodies in Prokaryotes: Recent Insights into Structure, Formation, and Relationship to Eukaryotic Lipid Depots

Neutral Lipid Bodies in Prokaryotes: Recent Insights into Structure, Formation, and Relationship to Eukaryotic Lipid Depots

PHB and Other Polhydroxyalkanoic Acids

The Ralstonia eutropha H16 phasin PhaP1 is targeted to intracellular triacylglycerol inclusions in Rhodococcus opacus PD630 and Mycobacterium smegmatis mc2155, and provides an anchor to target other proteins

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