Identification of a new class of biopolymer: bacterial synthesis of a sulfur-containing polymer with thioester linkages

Lütke‐Eversloh, Tina; Bergander, Klaus; Luftmann, Heinrich; Steinbüchel, Alexander

doi:10.1099/00221287-147-1-11

Cited by 166 publications

(143 citation statements)

References 31 publications

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“…The molecular masses of PHA polymers can range from 50 to 1,000 kDa or even above, and they may exhibit variable physical properties according to their monomer composition (244,245). The lack of specificity of PHA synthases is further underlined by their ability to synthesize polythioesters (PTE) by generating thioester bonds between 3-mercaptopropionic acid or other thiolic compounds (246,247).…”

Section: Pha Synthasesmentioning

confidence: 99%

Acyltransferases in Bacteria

Röttig

Steinbüchel

2013

Microbiol Mol Biol Rev

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148

141

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SUMMARY Long-chain-length hydrophobic acyl residues play a vital role in a multitude of essential biological structures and processes. They build the inner hydrophobic layers of biological membranes, are converted to intracellular storage compounds, and are used to modify protein properties or function as membrane anchors, to name only a few functions. Acyl thioesters are transferred by acyltransferases or transacylases to a variety of different substrates or are polymerized to lipophilic storage compounds. Lipases represent another important enzyme class dealing with fatty acyl chains; however, they cannot be regarded as acyltransferases in the strict sense. This review provides a detailed survey of the wide spectrum of bacterial acyltransferases and compares different enzyme families in regard to their catalytic mechanisms. On the basis of their studied or assumed mechanisms, most of the acyl-transferring enzymes can be divided into two groups. The majority of enzymes discussed in this review employ a conserved acyltransferase motif with an invariant histidine residue, followed by an acidic amino acid residue, and their catalytic mechanism is characterized by a noncovalent transition state. In contrast to that, lipases rely on completely different mechanism which employs a catalytic triad and functions via the formation of covalent intermediates. This is, for example, similar to the mechanism which has been suggested for polyester synthases. Consequently, although the presented enzyme types neither share homology nor have a common three-dimensional structure, and although they deal with greatly varying molecule structures, this variety is not reflected in their mechanisms, all of which rely on a catalytically active histidine residue.

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Section: Pha Synthasesmentioning

confidence: 99%

Acyltransferases in Bacteria

Röttig

Steinbüchel

2013

Microbiol Mol Biol Rev

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148

141

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“…Almost 150 different hydroxyalkanoic acids have now been described as constituents of PHAs (127). Interestingly, new polythioesters, in which the ester bonds between the building blocks were replaced by thioester bonds, were detected recently (89,90). The terminology for PHAs is based on the chain length of the incorporated hydroxy fatty acids and refers to PHA scl (short chain length [C3 to C5]) and PHA mcl (medium chain length [C6 to C14]).…”

Section: Occurrence and Function Of Storage Lipids In Prokaryotesmentioning

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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“…PHA synthases, which are the key enzymes of PHA biosynthesis, exhibit a very broad substrate spectrum and are capable of using a wide range of different hydroxyacyl coenzyme A (hydroxyacyl-CoA) thioesters as substrates for synthesis of these polyoxoesters. In addition, PHA synthases are also capable of biosynthesis of polythioesters, which are in contrast to polyoxoesters composed of mercaptoalkanoic acids (23,24). At present, all known PHA synthases can be assigned to one of four different classes according to their substrate ranges and their subunit compositions (32).…”

mentioning

confidence: 99%

Polyhydroxyalkanoate (PHA) Accumulation in Sulfate-Reducing Bacteria and Identification of a Class III PHA Synthase (PhaEC) in Desulfococcus multivorans

Hải

Lange

Rabus

et al. 2004

Appl Environ Microbiol

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Seven strains of sulfate-reducing bacteria (SRB) were tested for the accumulation of polyhydroxyalkanoates (PHAs). During growth with benzoate Desulfonema magnum accumulated large amounts of poly(3-hydroxybutyrate) [poly(3HB)]. Desulfosarcina variabilis (during growth with benzoate), Desulfobotulus sapovorans (during growth with caproate), and Desulfobacterium autotrophicum (during growth with caproate) accumulated poly(3HB) that accounted for 20 to 43% of cell dry matter. Desulfobotulus sapovorans and Desulfobacterium autotrophicum also synthesized copolyesters consisting of 3-hydroxybutyrate and 3-hydroxyvalerate when valerate was used as the growth substrate. Desulfovibrio vulgaris and Desulfotalea psychrophila were the only SRB tested in which PHAs were not detected. When total DNA isolated from Desulfococcus multivorans and specific primers deduced from highly conserved regions of known PHA synthases (PhaC) were used, a PCR product homologous to the central region of class III PHA synthases was obtained. The complete pha locus of Desulfococcus multivorans was subsequently obtained by inverse PCR, and it contained adjacent phaE Dm and phaC Dm genes. PhaC Dm and PhaE Dm were composed of 371 and 306 amino acid residues and showed up to 49 or 23% amino acid identity to the corresponding subunits of other class III PHA synthases. Constructs of phaC Dm alone (pBBRMCS-2::phaC Dm ) and of phaE Dm C Dm (pBBRMCS-2::phaE Dm C Dm ) in various vectors were obtained and transferred to several strains of Escherichia coli, as well as to the PHA-negative mutants PHB ؊ 4 and GPp104 of Ralstonia eutropha and Pseudomonas putida, respectively. In cells of the recombinant strains harboring phaE Dm C Dm small but significant amounts (up to 1.7% of cell dry matter) of poly(3HB) and of PHA synthase activity (up to 1.5 U/mg protein) were detected. This indicated that the cloned genes encode functionally active proteins. Hybrid synthases consisting of PhaC Dm and PhaE of Thiococcus pfennigii or Synechocystis sp. strain PCC 6308 were also constructed and were shown to be functionally active.Sulfate-reducing bacteria (SRB) are anaerobic bacteria that couple the oxidation of simple organic compounds (e.g., lactate) or of molecular hydrogen to the reduction of sulfate, which is the dominant electron acceptor in anaerobic zones of marine ecosystems, yielding the conspicuous end product hydrogen sulfide. SRB contribute significantly to the global cycling of carbon and sulfur, mineralizing more than 50% of the organic carbon via sulfate reduction in marine sediments (15,16). In addition, they also occur in brackish and freshwater habitats. SRB represent different genera and species, most of which are affiliated with the ␦ subgroup of the Proteobacteria, and they display a diversity of nutritional and catabolic properties (30,45,47). Besides their ecological role in carbon and sulfur cycles, SRB are also economically relevant, since they are implicated in corrosion of iron, concrete, and other materials (26). Despite a strong interest in the...

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Identification of a new class of biopolymer: bacterial synthesis of a sulfur-containing polymer with thioester linkages

Cited by 166 publications

References 31 publications

Acyltransferases in Bacteria

Acyltransferases in Bacteria

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

Polyhydroxyalkanoate (PHA) Accumulation in Sulfate-Reducing Bacteria and Identification of a Class III PHA Synthase (PhaEC) in Desulfococcus multivorans

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