The cytochrome b5-fold: An adaptable module

Lederer, Florence

doi:10.1016/0300-9084(94)90144-9

Cited by 91 publications

(104 citation statements)

References 171 publications

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“…The hydrophobicity plot (Kyte and Doolittle, 1982) after residue 200 showed the typical profile of membrane-bound desaturases (data not shown). The cytochrome b 5 -related domain contained the eight invariant residues typical for the cytochrome b 5 superfamily (Lederer, 1994). The N-terminal extension of about 100 residues did not share significant similarity to any sequence in the data banks, and computer analysis did not detect any motives for protein targeting or modification either for the extension or for the whole protein.…”

Section: Isolation Of a Full-length Cdnamentioning

confidence: 96%

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

et al. 1998

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SummaryThe moss Physcomitrella patens contains high levels of arachidonic acid. For its synthesis from linoleic acid by desaturation and elongation, novel ∆5-and ∆6-desaturases are required. To isolate one of these, PCR-based cloning was used, and resulted in the isolation of a full-length cDNA coding for a putatively new desaturase. The deduced amino acid sequence has three domains: a N-terminal segment of about 100 amino acids, with no similarity to any sequence in the data banks, followed by a cytochrome b 5 -related region and a C-terminal sequence with low similarity (27% identity) to acyl-lipid desaturases. To elucidate the function of this protein, we disrupted its gene by transforming P. patens with the corresponding linear genomic sequence, into which a positive selection marker had been inserted. The molecular analysis of five transformed lines showed that the selection cartridge had been inserted into the corresponding genomic locus of all five lines. The gene disruption resulted in a dramatic alteration of the fatty acid pattern in the knockout plants. The large increase in linoleic acid and the concomitant disappearance of γ-linolenic and arachidonic acid in all knockout lines suggested that the new cDNA coded for a ∆6-desaturase. This was confirmed by expression of the cDNA in yeast and analysis of the resultant fatty acids by GC-MS. Only the transformed yeast cells were able to introduce a further double bond into the ∆6-position of unsaturated fatty acids. To our knowledge, this is the first report of a successful gene disruption in a multicellular plant resulting in a specific biochemical phenotype.

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Section: Isolation Of a Full-length Cdnamentioning

confidence: 96%

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

et al. 1998

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“…BLAST searches using the Ole2 protein sequence revealed the presence of two conserved domains, a ⌬9 desaturase domain and a cytochrome B domain. Cytochrome B enzymes exhibit a wide range of properties and function in a large number of different redox processes (22). Therefore, Ole2 may be involved in PGE 2 production at the level of oxidation of AA.…”

Section: Vol 75 2007mentioning

confidence: 99%

Characterization of Prostaglandin E₂Production byCandida albicans

2007

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Candida albicans produces lipid metabolites that are functionally similar to host prostaglandins. These studies, using mass spectrometry, demonstrate that C. albicans produces authentic prostaglandin E 2 (PGE 2 ) from arachidonic acid. Maximal PGE 2 production was achieved at 37°C in stationary-phase culture supernatants and in cell-free lysates generated from stationary-phase cells. Interestingly, PGE 2 production is inhibited by both nonspecific cyclooxygenase and lipoxygenase inhibitors but not by inhibitors specific for the cyclooxygenase 2 isoenzyme. The C. albicans genome does not possess a cyclooxygenase homolog; however, several genes that may play a role in prostaglandin production from C. albicans were investigated. It was found that a C. albicans fatty acid desaturase homolog (Ole2) and a multicopper oxidase homolog (Fet3) play roles in prostaglandin production, with ole2/ole2 and fet3/fet3 mutant strains exhibiting reduced PGE 2 levels compared with parent strains. This work demonstrates that the synthesis of PGE 2 in C. albicans proceeds via novel pathways.The eicosanoids are a family of 20-carbon fatty acid metabolites that include prostaglandins and leukotrienes. Prostaglandin E 2 (PGE 2 ) is an oxygenated metabolite of arachidonic acid (AA) and is produced via a two-step process beginning with the initial action of a cyclooxygenase (COX-1 or COX-2) to form PGH 2 followed by specific PGE synthases in the mammalian host (4,16,42,43; reviewed in reference 26).

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“…The cytochrome b 5 -related domain contained the eight invariant residues typical for the cytochrome b 5 superfamily (marked with asterisks in Fig. 3) and the presence of a heme binding region characterized by the HPGG motif toward the N terminus (32). A heme-containing electron donor is required for fatty acid desaturation, and cytochrome b 5 fulfills this function for the membrane-bound desaturase (16,33,34).…”

Section: Cloning Of a P Patens Membrane-boundmentioning

confidence: 99%

Identification and Functional Characterization of the Moss Physcomitrella patens Δ5-Desaturase Gene Involved in Arachidonic and Eicosapentaenoic Acid Biosynthesis

Kaewsuwan

Cahoon

Perroud

et al. 2006

Journal of Biological Chemistry

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The moss Physcomitrella patens contains high levels of arachidonic acid and lesser amounts of eicosapentaenoic acid. Here we report the identification and characterization of a ⌬ 5 -desaturase from P. patens that is associated with the synthesis of these fatty acids. A full-length cDNA for this desaturase was identified by data base searches based on homology to sequences of known ⌬ 5 -desaturase cDNAs from fungal and algal species. The resulting P. patens cDNA encodes a 480-amino acid polypeptide that contains a predicted N-terminal cytochrome b 5 -like domain as well as three histidine-rich domains. Expression of the enzyme in Saccharomyces cerevisiae resulted in the production of the ⌬ 5 -containing fatty acid arachidonic acid in cells that were provided di-homo-␥-linolenic acid. In addition, the expressed enzyme generated ⌬ 5 -desaturation products with the C20 substrates -6 eicosadienoic and -3 eicosatrienoic acids, but no products were detected with the C18 fatty acid linoleic and ␣-linolenic acids or with the C22 fatty acid adrenic and docosapentaenoic acids. When the corresponding P. patens genomic sequence was disrupted by replacement through homologous recombination, a dramatic alteration in the fatty acid composition was observed, i.e. an increase in di-homo-␥-linolenic and eicosatetraenoic acids accompanied by a concomitant disappearance of the ⌬ 5 -fatty acid arachidonic and eicosapentaenoic acids. In addition, overexpression of the P. patens cDNA in protoplasts isolated from a disrupted line resulted in the restoration of arachidonic acid synthesis. Polyunsaturated fatty acids (PUFAs),4 fatty acids containing 18 or more carbon atoms with two or more methylene-interrupted double bonds in the cis-position, have received increasing attention in recent years because they are considered to have beneficial effects on human health and development when included in the diet (1, 2). Long-chain PUFAs (ՆC20) are not commonly found in angiosperms; however, they are present in some gymnosperms (3). High proportions of PUFA accumulation are found in many algae, mosses, and ferns (4 -6). The function of these long-chain PUFAs in the membranes of lower plants is still unclear, whereas in humans they play a role in eicosanoid metabolism (7). ) and EPA (20:5 ⌬ 5,8,11,14,17 ) are precursors of the short-lived regulatory molecules, the eicosanoids, that comprise the prostaglandins, the leukotrienes, and the thromboxanes (9 -11). These compounds act locally through autocrine or paracrine process on G-protein-linked cell surface receptors. This leads to the activation of various signaling mechanisms that have effects on numerous cellular functions including chemotaxis, vascular permeability, inflammation, vasoconstriction, regulation of the immune system, blood clotting, neurotransmission, and cholesterol metabolism (12)(13)(14). ARA (20:4 ⌬ 5,8,11,14 ) and EPA (20:5 ⌬ 5,8,11,14,17 ) are converted from linoleic acid (18:2 ⌬ 9,12) and ␣-linolenic acid (18:3 ⌬ 9,12,15 ), respectively, by the activities of ⌬ 6-desatura...

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The cytochrome b5-fold: An adaptable module

Cited by 91 publications

References 171 publications

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

Characterization of Prostaglandin E₂Production byCandida albicans

Identification and Functional Characterization of the Moss Physcomitrella patens Δ5-Desaturase Gene Involved in Arachidonic and Eicosapentaenoic Acid Biosynthesis

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The cytochrome b5-fold: An adaptable module

Cited by 91 publications

References 171 publications

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

Identification of a novel D6‐acyl‐group desaturase by targeted gene disruption in Physcomitrella patens

Characterization of Prostaglandin E2Production byCandida albicans

Identification and Functional Characterization of the Moss Physcomitrella patens Δ5-Desaturase Gene Involved in Arachidonic and Eicosapentaenoic Acid Biosynthesis

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Characterization of Prostaglandin E₂Production byCandida albicans