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  • 1
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2010
    In:  Applied Microbiology and Biotechnology Vol. 85, No. 6 ( 2010-2), p. 1713-1733
    In: Applied Microbiology and Biotechnology, Springer Science and Business Media LLC, Vol. 85, No. 6 ( 2010-2), p. 1713-1733
    Type of Medium: Online Resource
    ISSN: 0175-7598 , 1432-0614
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2010
    detail.hit.zdb_id: 1464336-4
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2013
    In:  European Journal of Lipid Science and Technology Vol. 115, No. 4 ( 2013-04), p. 394-404
    In: European Journal of Lipid Science and Technology, Wiley, Vol. 115, No. 4 ( 2013-04), p. 394-404
    Abstract: Acinetobacter baylyi synthesizes significant amounts of wax esters (WE) and triacylglycerols (TAG) catalyzed by wax ester synthase/acyl‐CoA:diacylglycerol acyltransferase (WS/DGAT or AtfA), representing the key enzyme for bacterial lipid accumulation. However, the structure and exact biochemical mechanism of AtfA could not be elucidated, yet. Therefore, a combination of random mutagenesis, screening and sequencing of atfA gene variants was conducted to gain further insights into the relationship between sequence and function of the enzyme. Several mutations could be detected which seriously diminished lipid accumulation in A. baylyi as well as AtfA activity in recombinant E. coli strains, such as Glu15Lys, Trp67Gly, Ala126Asp, Ser374Pro, or Gly378Ser/Asp. The affected residues are more or less conserved among a wide range of AtfA homologs. Especially the highly conserved pattern SNVPGP seems to be crucial, as mutations inside this pattern drastically impair enzyme activity. Furthermore, it became obvious that the C‐terminal part of AtfA is indispensable for activity, although the catalytic core is located in the N‐terminal half of the enzyme. In silico studies suggest that the C‐terminus might form a coiled‐coil fold which could putatively represent the dimerization domain. Practical applications: WE, composed of a long‐chain acyl moiety and a fatty alcohol residue, are valuable ingredients of many commercial products like cosmetics, medical products or lubricants. However, natural sources for high‐quality WE are currently mainly restricted to the expensive oil of the jojoba plant or to carnauba wax. As A. baylyi naturally accumulates WE with a similar composition to jojoba‐oil, this organisms and the responsible acyltransferase AtfA, are of great interest regarding a sustainable biotechnological WE production. However, a lack of structural knowledge about this enzyme family currently constricts promising enzyme optimization approaches. The insights gained by random mutagenesis of AtfA can build a basis for further site‐directed mutagenesis approaches in order to optimize its activity, stability, and/or substrate range.
    Type of Medium: Online Resource
    ISSN: 1438-7697 , 1438-9312
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2012720-0
    SSG: 21
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  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2021
    In:  Proceedings of the National Academy of Sciences Vol. 118, No. 11 ( 2021-03-16)
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 118, No. 11 ( 2021-03-16)
    Abstract: Cyanobacteria must prevent imbalances between absorbed light energy (source) and the metabolic capacity (sink) to utilize it to protect their photosynthetic apparatus against damage. A number of photoprotective mechanisms assist in dissipating excess absorbed energy, including respiratory terminal oxidases and flavodiiron proteins, but inherently reduce photosynthetic efficiency. Recently, it has been hypothesized that some engineered metabolic pathways may improve photosynthetic performance by correcting source/sink imbalances. In the context of this subject, we explored the interconnectivity between endogenous electron valves, and the activation of one or more heterologous metabolic sinks. We coexpressed two heterologous metabolic pathways that have been previously shown to positively impact photosynthetic activity in cyanobacteria, a sucrose production pathway (consuming ATP and reductant) and a reductant-only consuming cytochrome P450. Sucrose export was associated with improved quantum yield of phtotosystem II (PSII) and enhanced electron transport chain flux, especially at lower illumination levels, while cytochrome P450 activity led to photosynthetic enhancements primarily observed under high light. Moreover, coexpression of these two heterologous sinks showed additive impacts on photosynthesis, indicating that neither sink alone was capable of utilizing the full “overcapacity” of the electron transport chain. We find that heterologous sinks may partially compensate for the loss of photosystem I (PSI) oxidizing mechanisms even under rapid illumination changes, although this compensation is incomplete. Our results provide support for the theory that heterologous metabolism can act as a photosynthetic sink and exhibit some overlapping functionality with photoprotective mechanisms, while potentially conserving energy within useful metabolic products that might otherwise be “lost.”
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Elsevier BV ; 2015
    In:  Metabolic Engineering Vol. 32 ( 2015-11), p. 195-206
    In: Metabolic Engineering, Elsevier BV, Vol. 32 ( 2015-11), p. 195-206
    Type of Medium: Online Resource
    ISSN: 1096-7176
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
    detail.hit.zdb_id: 1471017-1
    SSG: 12
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  • 5
    In: International Journal of Systematic and Evolutionary Microbiology, Microbiology Society, Vol. 67, No. 10 ( 2017-10-01), p. 4057-4063
    Type of Medium: Online Resource
    ISSN: 1466-5026 , 1466-5034
    Language: English
    Publisher: Microbiology Society
    Publication Date: 2017
    detail.hit.zdb_id: 215062-1
    detail.hit.zdb_id: 2056611-6
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    American Society for Microbiology ; 2013
    In:  Microbiology and Molecular Biology Reviews Vol. 77, No. 2 ( 2013-06), p. 277-321
    In: Microbiology and Molecular Biology Reviews, American Society for Microbiology, Vol. 77, No. 2 ( 2013-06), p. 277-321
    Abstract: 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.
    Type of Medium: Online Resource
    ISSN: 1092-2172 , 1098-5557
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 2026768-X
    SSG: 12
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  • 7
    In: Plant Physiology, Oxford University Press (OUP), Vol. 189, No. 4 ( 2022-08-01), p. 2554-2566
    Abstract: Photosynthesis holds the promise of sustainable generation of useful products using light energy. Key to realizing this potential is the ability to rationally design photosynthesis to redirect energy and reductant derived from photons to desired products. Cytochrome P450s (P450s), which catalyze a broad array of reactions, have been engineered into a variety of photosynthetic organisms, where their activity has been shown to be photosynthesis-dependent, thus acting as heterologous sinks of electrons derived from photosynthesis. Furthermore, the addition of P450s can increase the photosynthetic capacity of the host organism. In this study, we developed this technology further using a P450 (CYP1A1) expressed in the cyanobacterium Synechococcus sp. PCC 7002. We show that rationally engineering photosynthesis by the removal of a competing electron sink, the respiratory terminal oxidase cytochrome c oxidase, increased the activity of CYP1A1. We provide evidence that this enhanced CYP1A1 activity was facilitated via an increase in the flux of electrons through Photosystem I. We also conducted a transcriptomic analysis on the designed strains to gain a more holistic understanding of how the cell responds to rational engineering. We describe a complex response including changes in expression of genes involved in photosynthesis and electron transfer linked to respiration. Specifically, the expression of CYP1A1 resulted in the reduction in expression of other natural electron dissipation pathways. This study emphasizes the potential for engineering photosynthetic organisms in biotechnology but also highlights the need to consider the broader impacts on cellular metabolism of any rationally induced changes.
    Type of Medium: Online Resource
    ISSN: 0032-0889 , 1532-2548
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2004346-6
    detail.hit.zdb_id: 208914-2
    SSG: 12
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  • 8
    In: Journal of Biotechnology, Elsevier BV, Vol. 225 ( 2016-05), p. 48-56
    Type of Medium: Online Resource
    ISSN: 0168-1656
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2016
    detail.hit.zdb_id: 2016476-2
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2017
    In:  Applied Microbiology and Biotechnology Vol. 101, No. 6 ( 2017-03), p. 2203-2216
    In: Applied Microbiology and Biotechnology, Springer Science and Business Media LLC, Vol. 101, No. 6 ( 2017-03), p. 2203-2216
    Type of Medium: Online Resource
    ISSN: 0175-7598 , 1432-0614
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 1464336-4
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  European Journal of Lipid Science and Technology Vol. 118, No. 1 ( 2016-01), p. 124-132
    In: European Journal of Lipid Science and Technology, Wiley, Vol. 118, No. 1 ( 2016-01), p. 124-132
    Abstract: For the biotechnical production of biofuels, oleo‐, or fine chemicals bacterial wax ester synthase/acyl‐Coenzyme A:diacylglycerol acyltransferases (WS/DGAT) are discussed as interesting candidates for in vivo esterification reactions. In this study, the suitability of selected acyltransferases for the conversion of non‐physiological substrates like short‐chain‐length alcohols and short‐chain length or even branched acyl‐CoAs has been investigated. In vitro analyzes of purified AtfA and AtfA(G355I) from Acinetobacter baylyi , Ma1(A360I) from Marinobacter aquaeolei , WS2 from Marinobacter hydrocarbonoclasticus , and AtfA1 from Alcanivorax borkumensis were conducted to evaluate the specific activities of these enzymes toward n‐hexadecanol (C 16 ), n‐dodecanol (C 12 ), ethanol (C 2 ), and methanol (C 1 ), palmitoyl‐CoA (C 16 ), butyryl‐CoA (C 4 ) as well as toward branched 3‐hydroxybutyryl‐CoA and 2‐hydroxyisobutyryl‐CoA. Athough long‐ and medium‐chain‐length substrates were preferred by all five enzymes, WS2 and AtfA showed the highest relative activities with ethanol or methanol when compared to n‐hexadecanol, whereas residual activities toward short or branched acyl‐CoAs could only be measured with AtfA and AtfA1. Practical applications: Bacterial WS/DGATs can be used for in vivo and in vitro approaches to synthesize custom‐made lipids, such as triglycerides or wax esters. However, due to their broad substrate ranges these enzymes are also promising candidates for the synthesis of other, industrially valuable oleo‐ and fine chemicals. Short‐chain‐length esters are important intermediates and building blocks for many production processes and, at present, there is a great demand for enzymes which are able to catalyze their synthesis. The physiological substrates of bacterial WS/DGAT enzymes are medium‐ to long‐chain length acyl‐CoAs and fatty alcohols to synthesize medium‐ to long‐chain length wax esters. In this study, we investigated five different bacterial WS/DGATs for their ability to synthesize short‐chain length esters, which represent biotechnologically interesting compounds. The enzymes AtfA, AtfA(G355I), Ma1(A360I), WS2, and AtfA1 were selected, purified, and characterized in vitro. In addition to the reference substrates, hexadecanol and palmitoyl‐CoA, their activity with dodecanol, ethanol, or methanol, on the one hand, and lauryl‐CoA, butyryl‐CoA, 3‐hydroxybutyryl‐CoA, or 2‐hydroxyisobutyryl‐CoA, on the other hand, were studied and compared.
    Type of Medium: Online Resource
    ISSN: 1438-7697 , 1438-9312
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 2012720-0
    SSG: 21
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