Calcineurin: Form and Function

2000 ◽  
Vol 80 (4) ◽  
pp. 1483-1521 ◽  
Author(s):  
Frank Rusnak ◽  
Pamela Mertz
Keyword(s):  
Protein Phosphatase ◽  
Metal Ion ◽  
Catalytic Mechanism ◽  
Quaternary Structure ◽  
Three Dimensional ◽  
Calcineurin Inhibitors ◽  
Spectroscopic Studies ◽  
Model Organisms ◽  
Dimensional Structure ◽  
Phosphate Ester

Calcineurin is a eukaryotic Ca2+- and calmodulin-dependent serine/threonine protein phosphatase. It is a heterodimeric protein consisting of a catalytic subunit calcineurin A, which contains an active site dinuclear metal center, and a tightly associated, myristoylated, Ca2+-binding subunit, calcineurin B. The primary sequence of both subunits and heterodimeric quaternary structure is highly conserved from yeast to mammals. As a serine/threonine protein phosphatase, calcineurin participates in a number of cellular processes and Ca2+-dependent signal transduction pathways. Calcineurin is potently inhibited by immunosuppressant drugs, cyclosporin A and FK506, in the presence of their respective cytoplasmic immunophilin proteins, cyclophilin and FK506-binding protein. Many studies have used these immunosuppressant drugs and/or modern genetic techniques to disrupt calcineurin in model organisms such as yeast, filamentous fungi, plants, vertebrates, and mammals to explore its biological function. Recent advances regarding calcineurin structure include the determination of its three-dimensional structure. In addition, biochemical and spectroscopic studies are beginning to unravel aspects of the mechanism of phosphate ester hydrolysis including the importance of the dinuclear metal ion cofactor and metal ion redox chemistry, studies which may lead to new calcineurin inhibitors. This review provides a comprehensive examination of the biological roles of calcineurin and reviews aspects related to its structure and catalytic mechanism.

The first crystal structure of the peptidase domain of the U32 peptidase family

2015 ◽  
Vol 71 (12) ◽  
pp. 2505-2512 ◽  
Author(s):  
Magdalena Schacherl ◽  
Angelika A. M. Montada ◽  
Elena Brunstein ◽  
Ulrich Baumann
Keyword(s):  
Crystal Structure ◽  
Catalytic Mechanism ◽  
Quaternary Structure ◽  
Catalytic Domain ◽  
Three Dimensional ◽  
Zinc Ion ◽  
Crystal Structure Analysis ◽  
Dimensional Structure ◽  
Sequence Motifs ◽  
Conserved Sequence

The U32 family is a collection of over 2500 annotated peptidases in the MEROPS database with unknown catalytic mechanism. They mainly occur in bacteria and archaea, but a few representatives have also been identified in eukarya. Many of the U32 members have been linked to pathogenicity, such as proteins fromHelicobacterandSalmonella. The first crystal structure analysis of a U32 catalytic domain fromMethanopyrus kandleri(genemk0906) reveals a modified (βα)8TIM-barrel fold with some unique features. The connecting segment between strands β7 and β8 is extended and helix α7 is located on top of the C-terminal end of the barrel body. The protein exhibits a dimeric quaternary structure in which a zinc ion is symmetrically bound by histidine and cysteine side chains from both monomers. These residues reside in conserved sequence motifs. No typical proteolytic motifs are discernible in the three-dimensional structure, and biochemical assays failed to demonstrate proteolytic activity. A tunnel in which an acetate ion is bound is located in the C-terminal part of the β-barrel. Two hydrophobic grooves lead to a tunnel at the C-terminal end of the barrel in which an acetate ion is bound. One of the grooves binds to aStrep-Tag II of another dimer in the crystal lattice. Thus, these grooves may be binding sites for hydrophobic peptides or other ligands.

Substitution of murine ferrochelatase glutamate-287 with glutamine or alanine leads to porphyrin substrate-bound variants

2001 ◽  
Vol 356 (1) ◽  
pp. 217-222 ◽  
Author(s):  
Ricardo FRANCO ◽  
Alice S. PEREIRA ◽  
Pedro TAVARES ◽  
Arianna MANGRAVITA ◽  
Michael J. BARBER ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Catalytic Mechanism ◽  
Protoporphyrin Ix ◽  
Three Dimensional ◽  
Iron Chelation ◽  
Enzymic Activity ◽  
Dimensional Structure ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Flow Experiments

Ferrochelatase (EC 4.99.1.1) is the terminal enzyme of the haem biosynthetic pathway and catalyses iron chelation into the protoporphyrin IX ring. Glutamate-287 (E287) of murine mature ferrochelatase is a conserved residue in all known sequences of ferrochelatase, is present at the active site of the enzyme, as inferred from the Bacillus subtilis ferrochelatase three-dimensional structure, and is critical for enzyme activity. Substitution of E287 with either glutamine (Q) or alanine (A) yielded variants with lower enzymic activity than that of the wild-type ferrochelatase and with different absorption spectra from the wild-type enzyme. In contrast to the wild-type enzyme, the absorption spectra of the variants indicate that these enzymes, as purified, contain protoporphyrin IX. Identification and quantification of the porphyrin bound to the E287-directed variants indicate that approx. 80% of the total porphyrin corresponds to protoporphyrin IX. Significantly, rapid stopped-flow experiments of the E287A and E287Q variants demonstrate that reaction with Zn2+ results in the formation of bound Zn-protoporphyrin IX, indicating that the endogenously bound protoporphyrin IX can be used as a substrate. Taken together, these findings suggest that the structural strain imposed by ferrochelatase on the porphyrin substrate as a critical step in the enzyme catalytic mechanism is also accomplished by the E287A and E287Q variants, but without the release of the product. Thus E287 in murine ferrochelatase appears to be critical for the catalytic process by controlling the release of the product.

The Construction of New Proteins. II. Design, Synthesis and Conformational Studies of Folding Units with βαβ-Topology

1986 ◽  
Vol 41 (10) ◽  
pp. 1315-1322 ◽  
Author(s):  
Manfred Mutter ◽  
Karl-Heinz Altmann ◽  
Thomas Vorherr
Keyword(s):  
Solid Phase ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Spectroscopic Studies ◽  
General Concept ◽  
Dimensional Structure ◽  
Design Synthesis ◽  
Phase Synthesis ◽  
Conformational Studies ◽  
Conformational Effects

The design, synthesis and preliminary conformational studies of two polypeptides exhibiting βαβ-type folding topologies are presented. In the design of the model peptides the general concept for the construction of new proteins developed in the preceeding paper was applied. According to this strategy, amphiphilic helices and β-sheets are linked together via hydrophilic loops to attain three-dimensional structures of higher order (‘supersecondary structures’). Com­puter-assisted molecular modelling served as a valuable tool for minimizing conformational con­straints within the molecules. The 38-residue peptide MI was synthesized using polyethylene glycol (PEG) as solubilizing polymeric support (‘Liquid-Phase synthesis'). Conformationally in­duced changes in the physico-chemical properties of the growing peptide chain stressed the significance of conformational effects in peptide synthesis reported earlier. Similar observations were made during the solid-phase synthesis of the 35-peptide MII. CD and IR spectroscopic studies revealed a high degree of secondary structure for both folding units. The present data strongly support the adoption of a three-dimensional structure for both models.

On the three-dimensional structure and catalytic mechanism of triose phosphate isomerase

1981 ◽  
Vol 293 (1063) ◽  
pp. 159-171 ◽  
Keyword(s):  
Catalytic Mechanism ◽  
Polypeptide Chain ◽  
Three Dimensional ◽  
Triose Phosphate Isomerase ◽  
Dimensional Structure ◽  
Dihydroxyacetone Phosphate ◽  
Triose Phosphate ◽  
Independent Determination ◽  
Chicken Muscle

Triose phosphate isomerase is a dimeric enzyme of molecular mass 56000 which catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate. The crystal structure of the enzyme from chicken muscle has been determined at a resolution of 2.5 A, and an independent determination of the structure of the yeast enzyme has just been completed at 3 A resolution. The conformation of the polypeptide chain is essentially identical in the two structures, and consists of an inner cylinder of eight strands of parallel |3-pleated sheet, with mostly helical segments connecting each strand. The active site is a pocket containing glutamic acid 165, which is believed to act as a base in the reaction. Crystallographic studies of the binding of DHAP to both the chicken and the yeast enzymes reveal a common mode of binding and suggest a mechanism for catalysis involving polarization of the substrate carbonyl group.

scholarly journals Structural characterization of quaternary selenites of tungsten(VI), A 2W3SeO12 (A = NH4, Cs, Rb, K or Tl)

2021 ◽  
Vol 77 (4) ◽  
pp. 406-411
Author(s):  
Vineela Balisetty ◽  
Kanamaluru Vidyasagar
Keyword(s):  
Three Dimensional ◽  
Spectroscopic Studies ◽  
Solid State Reactions ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Compound K ◽  
Three Dimensional Structure ◽  
Thermal And Spectroscopic Studies ◽  
Anionic Framework

The quaternary A 2W3SeO12 (A = NH4, Cs, Rb, K or Tl) selenites have been prepared in the form of single crystals by hydrothermal and novel solid-state reactions. They were characterized by X-ray diffraction, thermal and spectroscopic studies. All of them have a hexagonal tungsten oxide (HTO) related [W3SeO12]2− anionic framework with pyramidally coordinated Se4+ ions. The known A 2W3SeO12 (A = NH4, Cs or Rb) compounds are isostructural with the Cs2W3TeO12 compound and have a non-centrosymmetric layered structure containing intra-layer Se—O bonds. The new compound K2W3SeO12(α) is isostructural with the K2W3TeO12 compound and has a centrosymmetric three-dimensional structure containing interlayer Se—O bonds. It is inferred that the new Tl2W3SeO12 compound has the same three-dimensional structure as K2W3SeO12(α).

scholarly journals Antibodies against Thrombospondin-Related Anonymous Protein Do Not Inhibit Plasmodium Sporozoite Infectivity In Vivo

2000 ◽  
Vol 68 (6) ◽  
pp. 3667-3673 ◽  
Author(s):  
Soren Gantt ◽  
Cathrine Persson ◽  
Keith Rose ◽  
Ashley J. Birkett ◽  
Ruben Abagyan ◽  
...  
Keyword(s):  
Metal Ion ◽  
Competitive Inhibition ◽  
Polyclonal Antibodies ◽  
Three Dimensional ◽  
Calcium Ionophore ◽  
Plasmodium Yoelii ◽  
Gliding Motility ◽  
Vaccine Antigen ◽  
Dimensional Structure

ABSTRACT Thrombospondin-related anonymous protein (TRAP), a candidate malaria vaccine antigen, is required for Plasmodiumsporozoite gliding motility and cell invasion. For the first time, the ability of antibodies against TRAP to inhibit sporozoite infectivity in vivo is evaluated in detail. TRAP contains an A-domain, a well-characterized adhesive motif found in integrins. We modeled here a three-dimensional structure of the TRAP A-domain of Plasmodium yoelii and located regions surrounding the MIDAS (metal ion-dependent adhesion site), the presumed business end of the domain. Mice were immunized with constructs containing these A-domain regions but were not protected from sporozoite challenge. Furthermore, monoclonal and rabbit polyclonal antibodies against the A-domain, the conserved N terminus, and the repeat region of TRAP had no effect on the gliding motility or sporozoite infectivity to mice. TRAP is located in micronemes, secretory organelles of apicomplexan parasites. Accordingly, the antibodies tested here stained cytoplasmic TRAP brightly by immunofluorescence. However, very little TRAP could be detected on the surface of sporozoites. In contrast, a dramatic relocalization of TRAP onto the parasite surface occurred when sporozoites were treated with calcium ionophore. This likely mimics the release of TRAP from micronemes when a sporozoite contacts its target cell in vivo. Contact with hepatoma cells in culture also appeared to induce the release of TRAP onto the surface of sporozoites. If large amounts of TRAP are released in close proximity to its cellular receptor(s), effective competitive inhibition by antibodies may be difficult to achieve.

TonB or not TonB: is that the question?This paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (2) ◽  
pp. 87-97 ◽  
Author(s):  
Karla D. Krewulak ◽  
Hans J. Vogel
Keyword(s):  
Outer Membrane ◽  
Metal Ion ◽  
Peer Review Process ◽  
Three Dimensional ◽  
Membrane Receptor ◽  
Membrane Receptors ◽  
Dimensional Structure ◽  
Outer Membrane Receptor ◽  
Different Strains ◽  
Low Molecular Weight Iron

Bacteria are able to survive in low-iron environments by sequestering this metal ion from iron-containing proteins and other biomolecules such as transferrin, lactoferrin, heme, hemoglobin, or other heme-containing proteins. In addition, many bacteria secrete specific low molecular weight iron chelators termed siderophores. These iron sources are transported into the Gram-negative bacterial cell through an outer membrane receptor, a periplasmic binding protein (PBP), and an inner membrane ATP-binding cassette (ABC) transporter. In different strains the outer membrane receptors can bind and transport ferric siderophores, heme, or Fe3+ as well as vitamin B12, nickel complexes, and carbohydrates. The energy that is required for the active transport of these substrates through the outer membrane receptor is provided by the TonB/ExbB/ExbD complex, which is located in the cytoplasmic membrane. In this minireview, we will briefly examine the three-dimensional structure of TonB and the current models for the mechanism of TonB-dependent energy transduction. Additionally, the role of TonB in colicin transport will be discussed.

Metal Ion-Driven Assembly of Two New Coordination Polymers Constructed by Asymmetric Tricarboxylate and Imidazole-Containing Ligands: Syntheses, Crystal Structures, and Luminescent Properties

2015 ◽  
Vol 68 (1) ◽  
pp. 121 ◽  
Author(s):  
Wenlong Liu ◽  
Xueying Wang ◽  
Mengqiang Wu ◽  
Bing Wang
Keyword(s):  
Infrared Spectroscopy ◽  
Coordination Polymers ◽  
Metal Ion ◽  
Three Dimensional ◽  
Luminescent Properties ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Dimethyl Benzene

Two new coordination polymers, namely, {[Cd3(bpt)2(bimb)2]·2(H2O)}n (1) and [Zn3(bpt)2(bimb)2]n (2) (bpt = biphenyl-3,4′,5-tricarboxylate, bimb = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene), have been obtained under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterised by elemental analysis and infrared spectroscopy. Complex 1 exhibits a trinodal (4,4,4)-connected topology with Schläfli symbol of (4.62.83)4.(64.82). Complex 2 is also a three-dimensional structure and displays a (3,4,6)-connected topology with Schläfli symbol of (4.62)2.(42.66.85.102).(64.82). It is shown that the asymmetrically tricarboxylate can bear diverse structures regulated by metal ions. The photoluminescence behaviours of compounds 1 and 2 were also discussed.

scholarly journals Unusual quaternary structure of a homodimeric synergistic-type toxin from mamba snake venom defines its molecular evolution

2020 ◽  
Vol 477 (20) ◽  
pp. 3951-3962
Author(s):  
Narumi Aoki-Shioi ◽  
Chacko Jobichen ◽  
J. Sivaraman ◽  
R. Manjunatha Kini
Keyword(s):  
Disulfide Bond ◽  
Disulfide Bonds ◽  
Quaternary Structure ◽  
Hydrophobic Interactions ◽  
Biological Effects ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Common Structure

Snake venoms are complex mixtures of enzymes and nonenzymatic proteins that have evolved to immobilize and kill prey animals or deter predators. Among them, three-finger toxins (3FTxs) belong to the largest superfamily of nonenzymatic proteins. They share a common structure of three β-stranded loops extending like fingers from a central core containing all four conserved disulfide bonds. Most 3FTxs are monomers and through subtle changes in their amino acid sequences, they interact with different receptors, ion channels and enzymes to exhibit a wide variety of biological effects. The 3FTxs have further expanded their pharmacological space through covalent or noncovalent dimerization. Synergistic-type toxins (SynTxs) isolated from the deadly mamba venoms, although nontoxic, have been known to enhance the toxicity of other venom proteins. However, the details of three-dimensional structure and molecular mechanism of activity of this unusual class of 3FTxs are unclear. We determined the first three-dimensional structure of a SynTx isolated from Dendroaspis jamesoni jamesoni (Jameson's mamba) venom. The SynTx forms a unique homodimer that is held together by an interchain disulfide bond. The dimeric interface is elaborate and encompasses loops II and III. In addition to the inter-subunit disulfide bond, the hydrogen bonds and hydrophobic interactions between the monomers contribute to the dimer formation. Besides, two sulfate ions that mediate interactions between the monomers. This unique quaternary structure is evolved through noncovalent homodimers such as κ-bungarotoxins. This novel dimerization further enhances the diversity in structure and function of 3FTxs.

scholarly journals Role of Pro-297 in the catalytic mechanism of sheep liver serine hydroxymethyltransferase

2000 ◽  
Vol 350 (3) ◽  
pp. 849-853 ◽  
Author(s):  
Rashmi TALWAR ◽  
Vijayapandian LEELAVATHY ◽  
Jala V. KRISHNA RAO ◽  
Naropantul APPAJI RAO ◽  
Handanahal S. SAVITHRI
Keyword(s):  
Aspartate Aminotransferase ◽  
Catalytic Mechanism ◽  
Three Dimensional ◽  
Proton Exchange ◽  
Serine Hydroxymethyltransferase ◽  
Dimensional Structure ◽  
Transamination Reaction ◽  
Reaction Specificity ◽  
High Degree

Serine hydroxymethyltransferase belongs to the α class of pyridoxal-5´-phosphate enzymes along with aspartate aminotransferase. Recent reports on the three-dimensional structure of human liver cytosolic serine hydroxymethyltransferase had suggested a high degree of similarity between the active-site geometries of the two enzymes. A comparison of the sequences of serine hydroxymethyltransferases revealed the presence of several highly conserved residues, including Pro-297. This residue is equivalent to residue Arg-292 of aspartate aminotransferase, which binds the γ-carboxy group of aspartate. In an attempt to change the reaction specificity of the hydroxymethyltransferase to that of an aminotransferase and to assign a possible reason for the conserved nature of Pro-297, it was mutated to Arg. The mutation decreased the hydroxymethyltransferase activity significantly (by 85–90%) and abolished the ability to catalyse alternative reactions, without alteration in the oligomeric structure, pyridoxal 5´-phosphate content or substrate binding. However, the concentration of the quinonoid intermediate and the extent of proton exchange was decreased considerably (by approx. 85%) corresponding to the decrease in catalytic activity. Interestingly, mutant Pro-297 Arg was unable to perform the transamination reaction with l-aspartate. All these results suggest that although Pro-297 is indirectly involved in catalysis, it might not have any role in imparting substrate specificity, unlike the similarly positioned Arg-292 in aspartate aminotransferase.

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