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Häfner AK, Beilstein K, Graab P, Ball AK, Saul MJ, Hofmann B, Steinhilber D. Identification and Characterization of a New Protein Isoform of Human 5-Lipoxygenase. PLoS One 2016; 11:e0166591. [PMID: 27855198 PMCID: PMC5113960 DOI: 10.1371/journal.pone.0166591] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 10/31/2016] [Indexed: 11/18/2022] Open
Abstract
Leukotrienes (LTs) are inflammatory mediators that play a pivotal role in many diseases like asthma bronchiale, atherosclerosis and in various types of cancer. The key enzyme for generation of LTs is the 5-lipoxygenase (5-LO). Here, we present a novel putative protein isoform of human 5-LO that lacks exon 4, termed 5-LOΔ4, identified in cells of lymphoid origin, namely the Burkitt lymphoma cell lines Raji and BL41 as well as primary B and T cells. Deletion of exon 4 does not shift the reading frame and therefore the mRNA is not subjected to non-mediated mRNA decay (NMD). By eliminating exon 4, the amino acids Trp144 until Ala184 are omitted in the corresponding protein. Transfection of HEK293T cells with a 5-LOΔ4 expression plasmid led to expression of the corresponding protein which suggests that the 5-LOΔ4 isoform is a stable protein in eukaryotic cells. We were also able to obtain soluble protein after expression in E. coli and purification. The isoform itself lacks canonical enzymatic activity as it misses the non-heme iron but it still retains ATP-binding affinity. Differential scanning fluorimetric analysis shows two transitions, corresponding to the two domains of 5-LO. Whilst the catalytic domain of 5-LO WT is destabilized by calcium, addition of calcium has no influence on the catalytic domain of 5-LOΔ4. Furthermore, we investigated the influence of 5-LOΔ4 on the activity of 5-LO WT and proved that it stimulates 5-LO product formation at low protein concentrations. Therefore regulation of 5-LO by its isoform 5-LOΔ4 might represent a novel mechanism of controlling the biosynthesis of lipid mediators.
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Affiliation(s)
- Ann-Kathrin Häfner
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- * E-mail: (DS); (A-KH)
| | - Kim Beilstein
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Philipp Graab
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Ann-Katrin Ball
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Meike J. Saul
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- Department of Biology, Technical University of Darmstadt, 64287, Darmstadt, Germany
| | - Bettina Hofmann
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Dieter Steinhilber
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- * E-mail: (DS); (A-KH)
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Rådmark O, Werz O, Steinhilber D, Samuelsson B. 5-Lipoxygenase, a key enzyme for leukotriene biosynthesis in health and disease. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:331-9. [PMID: 25152163 DOI: 10.1016/j.bbalip.2014.08.012] [Citation(s) in RCA: 336] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/13/2014] [Accepted: 08/14/2014] [Indexed: 12/21/2022]
Abstract
5-Lipoxygenase (5-LOX) catalyzes two steps in the biosynthesis of leukotrienes (LTs), lipid mediators of inflammation derived from arachidonic acid. In this review we focus on 5-LOX biochemistry including 5-LOX interacting proteins and regulation of enzyme activity. LTs function in normal host defense, and have roles in many disease states where acute or chronic inflammation is part of the pathophysiology, as briefly summarized at the end of this chapter. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".
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Affiliation(s)
- Olof Rådmark
- Dept of Medical Biochemistry and Biophysics, Div. of Chemistry II, Karolinska Institutet, Sweden
| | - Oliver Werz
- Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University Jena, Germany
| | - Dieter Steinhilber
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Germany
| | - Bengt Samuelsson
- Dept of Medical Biochemistry and Biophysics, Div. of Chemistry II, Karolinska Institutet, Sweden
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Okamoto H, Hammarberg T, Zhang YY, Persson B, Watanabe T, Samuelsson B, Rådmark O. Mutation analysis of the human 5-lipoxygenase C-terminus: support for a stabilizing C-terminal loop. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1749:123-31. [PMID: 15848143 DOI: 10.1016/j.bbapap.2005.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 03/09/2005] [Accepted: 03/09/2005] [Indexed: 10/25/2022]
Abstract
Lipoxygenases contain prosthetic iron, in human 5-lipoxygenase (5LO) the C-terminal isoleucine carboxylate constitutes one of five identified ligands. ATP is one of several factors determining 5LO activity. We compared properties of a series of 5LO C-terminal deletion mutants (one to six amino acid residues deleted). All mutants were enzymatically inactive (expected due to loss of iron), but expression yield (in E. coli) and affinity to ATP-agarose was markedly different. Deletion of up to four C-terminal residues was compatible with good expression and retained affinity to the ATP-column, as for wild-type 5LO. However when also the fifth residue was deleted (Asn-669) expression yield decreased and the affinity to ATP was markedly diminished. This was interpreted as a result of deranged structure and stability, due to loss of a hydrogen bond between Asn-669 and His-399. Mutagenesis of these residues supported this conclusion. In the structure of soybean lipoxygenase-1, a C-terminal loop was pointed out as important for correct orientation of the C-terminus. Accordingly, a hydrogen bond appears to stabilize such a C-terminal loop also in 5LO.
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Affiliation(s)
- Hisayo Okamoto
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
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Abstract
In this article, it has been attempted to review data primarily on the activation of human 5-lipoxygenase, in vitro and in the cell. First, structural properties and enzyme activities are described. This is followed by the activating factors: Ca2+, membranes, ATP, and lipid hydroperoxide. Also, studies on phosphorylation of 5-lipoxygenase, interaction with other proteins, and the intracellullar mobility of 5-lipoxygenase, are reviewed.
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Affiliation(s)
- Olof Rådmark
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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Jisaka M, Boeglin WE, Kim RB, Brash AR. Site-Directed Mutagenesis Studies on a Putative Fifth Iron Ligand of Mouse 8S-Lipoxygenase: Retention of Catalytic Activity on Mutation of Serine-558 to Asparagine, Histidine, or Alanine. Arch Biochem Biophys 2001; 386:136-42. [PMID: 11368335 DOI: 10.1006/abbi.2000.2175] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The reported crystal structures of plant and animal lipoxygenases (LOX) show that the nonheme iron in the catalytic domain is ligated by three histidines, the C-terminal isoleucine, and in certain structures also by a fifth iron ligand, an asparagine or histidine residue. Mouse 8-LOX and its homologues (e.g., human 15-LOX-2) are unique in having a serine in place of the usual Asn or His in this fifth position. To investigate the importance of the residue in mouse 8-LOX structure-function, the serine-558 was replaced by asparagine, histidine, or alanine using oligonucleotide-directed mutagenesis. Wild-type mouse 8-LOX and the mutant cDNAs were expressed in HeLa cells infected with vaccinia virus encoding T7 RNA polymerase and their relative lipoxygenase activities assessed by incubation with [14C]arachidonic acid or [14C]linoleic acid followed by HPLC analysis of the products. The Ser558Asn and Ser558His mutants had equivalent or greater activity than wild-type 8-LOX. They also exhibited some 15-LOX activity, indicating that small structural perturbations (in this case to a residue identical in mouse 8-LOX and its 15-LOX-2 homologues) can interchange the positional specificity of these closely related enzymes. Remarkably, the Ser558Ala mutant exhibited significant 8-LOX activity, indicating that this position is not an essential iron ligand in the enzyme. We conclude that mouse 8-LOX is catalytically competent with only four amino acid iron ligands, and that Ser-558 of the wild-type enzyme does not play an essential role in catalysis.
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Affiliation(s)
- M Jisaka
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602, USA.
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Affiliation(s)
- O Rådmark
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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Hammarberg T, Zhang YY, Lind B, Radmark O, Samuelsson B. Mutations at the C-terminal isoleucine and other potential iron ligands of 5-lipoxygenase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:401-7. [PMID: 7607208 DOI: 10.1111/j.1432-1033.1995.0401h.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The non-heme iron centre in human 5-lipoxygenase was studied. Recombinant enzyme was expressed in Escherichia coli, purified and assayed for iron content and enzyme activity. For non-mutated enzyme, the iron content was 1.01 +/- 0.19 mol/mol. Deletion of the C-terminal Ile673 resulted in an iron content of 0.03 +/- 0.07 mol/mol and undetectable lipoxygenase activity. Mutations at His367, Glu376 and Asn554 led to drastically decreased enzyme activity (< 2% of non-mutated control) but iron was still present. In addition to Glu376, eight other conserved acidic residues (Asp/Glu) in 5-lipoxygenase were replaced, none of which was crucial for enzyme activity. We conclude that Ile673 is an iron ligand in 5-lipoxygenase, while our results do not support that Glu376 or Asn554 have this function. The possible role of His367 as a replaceable iron ligand is discussed.
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Affiliation(s)
- T Hammarberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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Chasteen ND, Grady JK, Skorey KI, Neden KJ, Riendeau D, Percival MD. Characterization of the non-heme iron center of human 5-lipoxygenase by electron paramagnetic resonance, fluorescence, and ultraviolet-visible spectroscopy: redox cycling between ferrous and ferric states. Biochemistry 1993; 32:9763-71. [PMID: 8396969 DOI: 10.1021/bi00088a031] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Purified human 5-lipoxygenase, a non-heme iron containing enzyme, has been characterized by electron paramagnetic resonance, (EPR), ultraviolet (UV)-visible and fluorescence spectroscopy. As isolated, the enzyme is largely in the ferrous state and shows a weak X-band EPR signal extending from 0 to 700 G at 15 K, tentatively ascribed to integer spin Fe(II). Titration of the protein with 13-HPOD (13-hydroperoxyoctadecadienoic acid) generates a strong multicomponent EPR signal in the g' approximately 6 region, a yellow color associated with an increased absorption between 310 and 450 nm (epsilon 330nm = 2400 M-1 cm-1), and a 17% decrease in the intrinsic protein fluorescence. The multiple component nature of the g' approximately 6 signal indicates that the metal center in its oxidized state exists in more than one but related forms. The g' approximately 6 EPR signal and the yellow color reach a maximum when approximately 1 mol of 13-HPOD is added/mol of iron; the resultant EPR spectrum accounts quantitatively for all of the iron in the protein with a signal at g' = 4.3 representing less than 3% of the total iron in the majority of samples. Addition of a hydroxyurea reducing agent abolished the g' approximately 6 signal and yellow color of the protein and also reversed the decrease in fluorescence caused by the oxidant 13-HPOD. The results indicate that the g' approximately 6 EPR signal, the yellow color, and the decreased fluorescence are associated with the formation of the Fe(III) form of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N D Chasteen
- Department of Chemistry, University of New Hampshire, Durham 03824
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Minor W, Steczko J, Bolin JT, Otwinowski Z, Axelrod B. Crystallographic determination of the active site iron and its ligands in soybean lipoxygenase L-1. Biochemistry 1993; 32:6320-3. [PMID: 8518276 DOI: 10.1021/bi00076a003] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Five ligands of the active site iron atom in soybean lipoxygenase L-1 have been identified from the electron density map of the crystallized enzyme. The position of the iron atom can be readily and independently located from an anomalous difference electron density map. The ligands identified are His-499, His-504, His-690, Asn-694, and Ile-839, the carboxy-terminal residue. Our previous view that these three histidines are essential for activity and binding of iron, based on site-specific mutation studies, is confirmed. A sixth protein ligand is not present, and the sixth coordination site opens into a wide cleft. The structure of the soybean lipoxygenase was solved by multiple anomalous isomorphous replacements.
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Affiliation(s)
- W Minor
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
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