Prostaglandins and leukotrienes are potent eicosanoid lipid mediators derived from phospholipase-released arachidonic acid that are involved in numerous homeostatic biological functions and inflammation. They are generated by cyclooxygenase isozymes and 5-lipoxygenase, respectively, and their biosynthesis and actions are blocked by clinically relevant nonsteroidal anti-inflammatory drugs, the newer generation coxibs (selective inhibitors of cyclooxygenase-2), and leukotriene modifiers. The prime mode of prostaglandin and leukotriene action is through specific G protein-coupled receptors, many of which have been cloned recently, thus enabling specific receptor agonist and antagonist development. Important insights into the mechanisms of inflammatory responses, pain, and fever have been gleaned from our current understanding of eicosanoid biology.

https://science.sciencemag.org/content/sci/294/5548/1871.full.pdf

Prostaglandins and Leukotrienes: Advances in Eicosanoid Biology

ARP/wARP is a software suite to build macromolecular models in X-ray crystallography electron density maps. Structural genomics initiatives and the study of complex macromolecular assemblies and membrane proteins all rely on advanced methods for 3D structure determination. ARP/wARP meets these needs by providing the tools to obtain a macromolecular model automatically, with a reproducible computational procedure. ARP/wARP 7.0 tackles several tasks: iterative protein model building including a high-level decision-making control module; fast construction of the secondary structure of a protein; building flexible loops in alternate conformations; fully automated placement of ligands, including a choice of the best-fitting ligand from a 'cocktail'; and finding ordered water molecules. All protocols are easy to handle by a nonexpert user through a graphical user interface or a command line. The time required is typically a few minutes although iterative model building may take a few hours.

/pdf/automated-macromolecular-model-building-for-x-ray-w903jv6gcj.pdf

Automated macromolecular model building for X-ray crystallography using ARP/wARP version 7.

The ability to control cell volume is pivotal for cell function. Cell volume perturbation elicits a wide array of signaling events, leading to protective (e.g., cytoskeletal rearrangement) and adap...

Physiology of cell volume regulation in vertebrates.

Glutathione catalysis and the reaction mechanisms of glutathione-dependent enzymes.

4. Biosynthesis of Leukotrienes 5869 4.1. Discovery of the Leukotriene Pathway and a Common Unstable Intermediate 5869 4.2. Conversion of Arachidonic Acid into Leukotriene A4 (LTA4) Is a Two-Step Concerted Reaction Catalyzed by a Single Lipoxygenase 5869 4.3. Structural Elucidation of Slow-Reacting Substance of Anaphylaxis, A Mixture of Leukotrienes 5870 5. Enzymes and Proteins in Leukotriene Biosynthesis 5870 5.1. Cytosolic Phospholipase A2α (cPLA2α) 5870 5.1.1. Molecular Properties and Regulation of cPLA2α 5870 5.1.2. Crystal Structure and Catalytic Mechanism of cPLA2α 5871 5.2. 5-Lipoxygenase (5-LO) 5871 5.2.1. Cellular Expression of 5-LO 5871 5.2.2. Regulation of 5-LO Gene (ALOX5) Transcription 5872 5.2.3. Naturally Occurring Mutations in the Gene Promoter of 5-LO 5872 5.2.4. Allosteric and Post-translational Regulation of 5-LO 5872 5.2.5. Structure function relationships in 5-LO 5872 5.2.6. Crystal Structure of 5-LO 5872 5.3. 5-Lipoxygenase-Activating Protein (FLAP) 5873 5.3.1. FLAP Is Critical for Cellular 5-LO Activity 5873 5.3.2. Effects of FLAP on Leukotriene Production 5873 5.3.3. FLAP Gene (ALOX5AP) and Regulation of Expression 5874 5.3.4. Crystal Structure of FLAP 5874 5.4. LTA4 Hydrolase 5874 5.4.1. LTA4 Hydrolase Is a Substrate-Selective and Suicide-Inactivated Epoxide Hydrolase 5874 5.4.2. LTA4 Hydrolase Is Bifunctional and Belongs to the M1 Family of Zinc Metallopeptidases 5874 5.4.3. LTA4 Hydrolase Cleaves the Chemotactic Pro-Gly-Pro, a Role for the Aminopeptidase Activity during Resolution of Inflammation 5875 5.4.4. Crystal Structure of LTA4 Hydrolase 5875 5.4.5. Mechanism of the Epoxide Hydrolase Reaction 5876 5.4.6. Mechanism of the Aminopeptidase Activity 5876 5.4.7. Two Catalytic Activities Exerted via Specific but Overlapping Active Sites 5877 5.5. LTC4 Synthase 5877 5.5.1. Molecular Properties of LTC4 Synthase 5877 5.5.2. LTC4 Synthase Is a Member of the MAPEG Superfamily of IntegralMembraneProteins 5877 5.5.3. Gene Structure and Regulation of LTC4 Synthase Expression 5877 5.5.4. Crystal Structure of LTC4 Synthase 5877 5.5.5. Catalytic Mechanism of LTC4 Synthase 5878 6. Intracellular Protein Trafficking and Compartmentalization of Leukotriene Biosynthesis 5878 6.1. Translocation of cPLA2α 5878 6.2. Translocation of 5-LO and Association with FLAP on the Nuclear Envelope 5879 6.2.1. 5-LO in the Nucleoplasm 5879 6.2.2. Organization of a Leukotriene Biosynthetic Complex in the Nuclear Membrane 5879 6.3. Leukotriene Biosynthesis in Lipid Bodies and Actions on Extracellular Granules 5879

Lipoxygenase and leukotriene pathways: biochemistry, biology, and roles in disease.

Cysteinyl leukotrienes are key mediators in inflammation and have an important role in acute and chronic inflammatory diseases of the cardiovascular and respiratory systems, in particular bronchial 

Structural Basis for Synthesis of Inflammatory Mediators by Human Leukotriene C4 Synthase.

The N-terminal Domain of 5-Lipoxygenase Binds Calcium and Mediates Calcium Stimulation of Enzyme Activity

5-Lipoxygenase Interacts with Coactosin-like Protein

5-Lipoxygenase (5LO) catalyzes the first two steps in the biosynthesis of leukotrienes and lipoxins and has therefore become an important target for pharmacological treatment of inflammatory disorders. Binding of calcium to 5LO was shown using several different approaches. Human recombinant enzyme was expressed in E. coli and purified. Association of Ca2+ to 5LO was demonstrated by a calcium-induced mobility shift in gel electrophoresis, by calcium overlay, by gel filtration in the presence of calcium, and by equilibrium dialysis. The two latter methods also showed that calcium binds reversibly to 5LO. Equilibrium dialysis gave a Kd close to 6 μM; the stoichiometry of maximum calcium binding seemed to average around two Ca2+ per 5LO. Similar results were obtained when 5LO was inactivated during equilibrium dialysis, indicating that the calcium binding site(s) is (are) different from the active site. By Triton X-114 partitioning, it was confirmed that calcium increases the hydrophobicity of 5LO.

5-Lipoxygenase Binds Calcium†

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.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1995.0401h.x

Tove Hammarberg

Papers

Structural Basis for Synthesis of Inflammatory Mediators by Human Leukotriene C4 Synthase.

The N-terminal Domain of 5-Lipoxygenase Binds Calcium and Mediates Calcium Stimulation of Enzyme Activity

5-Lipoxygenase Interacts with Coactosin-like Protein

5-Lipoxygenase Binds Calcium†

Mutations at the C-terminal isoleucine and other potential iron ligands of 5-lipoxygenase