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Wang Y, Desbois M, Udyavar A, Ryner L, Kozlowski C, Guan Y, Dürrbaum M, Lu S, Fortin JP, Koeppen H, Ziai J, Chang CW, Lo A, Keerthivasan S, Plante M, Bais C, Hegde P, Daemen A, Turley S. Targeting molecular mediators of T cell exclusion for effective immunotherapy in ovarian cancer. Ann Oncol 2019. [DOI: 10.1093/annonc/mdz268.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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2
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Braude I, Vukovic B, Prasad M, Marrano P, Turley S, Barber D, Zielenska M, Squire JA. Large scale copy number variation (CNV) at 14q12 is associated with the presence of genomic abnormalities in neoplasia. BMC Genomics 2006; 7:138. [PMID: 16756668 PMCID: PMC1550726 DOI: 10.1186/1471-2164-7-138] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 06/06/2006] [Indexed: 01/03/2023] Open
Abstract
Background Advances made in the area of microarray comparative genomic hybridization (aCGH) have enabled the interrogation of the entire genome at a previously unattainable resolution. This has lead to the discovery of a novel class of alternative entities called large-scale copy number variations (CNVs). These CNVs are often found in regions of closely linked sequence homology called duplicons that are thought to facilitate genomic rearrangements in some classes of neoplasia. Recently, it was proposed that duplicons located near the recurrent translocation break points on chromosomes 9 and 22 in chronic myeloid leukemia (CML) may facilitate this tumor-specific translocation. Furthermore, ~15–20% of CML patients also carry a microdeletion on the derivative 9 chromosome (der(9)) and these patients have a poor prognosis. It has been hypothesised that der(9) deletion patients have increased levels of chromosomal instability. Results In this study aCGH was performed and identified a CNV (RP11-125A5, hereafter called CNV14q12) that was present as a genomic gain or loss in 10% of control DNA samples derived from cytogenetically normal individuals. CNV14q12 was the same clone identified by Iafrate et al. as a CNV. Real-time polymerase chain reaction (Q-PCR) was used to determine the relative frequency of this CNV in DNA from a series of 16 CML patients (both with and without a der(9) deletion) together with DNA derived from 36 paediatric solid tumors in comparison to the incidence of CNV in control DNA. CNV14q12 was present in ~50% of both tumor and CML DNA, but was found in 72% of CML bearing a der(9) microdeletion. Chi square analysis found a statistically significant difference (p ≤ 0.001) between the incidence of this CNV in cancer and normal DNA and a slightly increased incidence in CML with deletions in comparison to those CML without a detectable deletion. Conclusion The increased incidence of CNV14q12 in tumor samples suggests that either acquired or inherited genomic variation of this new class of variation may be associated with onset or progression of neoplasia.
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Affiliation(s)
- Ilan Braude
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Bisera Vukovic
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Mona Prasad
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Paula Marrano
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Stefanie Turley
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Dwayne Barber
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Maria Zielenska
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Department of Paediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jeremy A Squire
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- The Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
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3
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Hol W, Deng J, Abendroth J, Mitchell D, Yanez M, Roach C, Krumm B, Turley S. Molecular machines and tropical pathogens. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305096078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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4
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Cheon SS, Cheah AYL, Turley S, Nadesan P, Poon R, Clevers H, Alman BA. beta-Catenin stabilization dysregulates mesenchymal cell proliferation, motility, and invasiveness and causes aggressive fibromatosis and hyperplastic cutaneous wounds. Proc Natl Acad Sci U S A 2002; 99:6973-8. [PMID: 11983872 PMCID: PMC124513 DOI: 10.1073/pnas.102657399] [Citation(s) in RCA: 269] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2001] [Indexed: 02/08/2023] Open
Abstract
Fibroproliferative processes are a group of disorders in which there is excessive proliferation of spindle (mesenchymal fibroblast-like) cells. They range from hypertrophic scars to neoplasms such as aggressive fibromatosis. Cells from these disorders share cytologic similarity with fibroblasts present during the proliferative phase of wound healing, suggesting that they represent a prolonged wounding response. A critical role for beta-catenin in mesenchymal cells in fibroproliferative processes is suggested by its high rate of somatic mutation in aggressive fibromatosis. Using a Tcf-reporter mouse we found that beta-catenin protein level and Tcf-transcriptional activity are elevated in fibroblasts during the proliferative phase of healing. We generated a transgenic mouse in which stabilized beta-catenin is expressed in mesenchymal cells under control of a tetracycline-regulated promoter. Fibroblasts from the transgenic mice exhibited increased proliferation, motility, and invasiveness when expressing stabilized beta-catenin and induced tumors after induction of the transgene when grafted into nude mice. Mice developed aggressive fibromatoses and hyperplastic gastrointestinal polyps after 3 months of transgene induction and healed with hyperplastic cutaneous wounds compared with control mice, which demonstrates an important function for beta-catenin in mesenchymal cells and shows a central role for beta-catenin in wound healing and fibroproliferative disorders.
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Affiliation(s)
- Sophia S Cheon
- Program in Developmental Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
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5
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Kumar A, Roach C, Hirsh IS, Turley S, deWalque S, Michels PA, Hol WG. An unexpected extended conformation for the third TPR motif of the peroxin PEX5 from Trypanosoma brucei. J Mol Biol 2001; 307:271-82. [PMID: 11243819 DOI: 10.1006/jmbi.2000.4465] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A number of helix-rich protein motifs are involved in a variety of critical protein-protein interactions in living cells. One of these is the tetratrico peptide repeat (TPR) motif that is involved, amongst others, in cell cycle regulation, chaperone function and post-translation modifications. So far, these helix-rich TPR motifs have always been observed to be a compact unit of two helices interacting with each other in antiparallel fashion. Here, we describe the structure of the first three TPR-motifs of the peroxin PEX5 from Trypanosoma brucei, the causative agent of sleeping sickness. Peroxins are proteins involved in peroxisome, glycosome and glyoxysome biogenesis. PEX5 is the receptor of the proteins targeted to these organelles by the "peroxisomal targeting signal-1", a C-terminal tripeptide called PTS-1. The first two of the three TPR-motifs of T. brucei PEX5 appear to adopt the canonical antiparallel helix hairpin structure. In contrast, the third TPR motif of PEX5 has a dramatically different conformation in our crystals: the two helices that were supposed to form a hairpin are folded into one single 44 A long continuous helix. Such a conformation has never been observed before for a TPR motif. This raises interesting questions including the potential functional importance of a "jack-knife" conformational change in TPR motifs.
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Affiliation(s)
- A Kumar
- Departments of Biological Structure and Biochemistry, Biomolecular Structure Center and Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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6
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Buhman KK, Accad M, Novak S, Choi RS, Wong JS, Hamilton RL, Turley S, Farese RV. Resistance to diet-induced hypercholesterolemia and gallstone formation in ACAT2-deficient mice. Nat Med 2000; 6:1341-7. [PMID: 11100118 DOI: 10.1038/82153] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The importance of cholesterol ester synthesis by acyl CoA:cholesterol acyltransferase (ACAT) enzymes in intestinal and hepatic cholesterol metabolism has been unclear. We now demonstrate that ACAT2 is the major ACAT in mouse small intestine and liver, and suggest that ACAT2 deficiency has profound effects on cholesterol metabolism in mice fed a cholesterol-rich diet, including complete resistance to diet-induced hypercholesterolemia and cholesterol gallstone formation. The underlying mechanism involves the lack of cholesterol ester synthesis in the intestine and a resultant reduced capacity to absorb cholesterol. Our results indicate that ACAT2 has an important role in the response to dietary cholesterol, and suggest that ACAT2 inhibition may be a useful strategy for treating hypercholesterolemia or cholesterol gallstones.
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Affiliation(s)
- K K Buhman
- Gladstone Institute of Cardiovascular Disease, P.O. Box 419100, San Francisco, California 94141-9100, USA
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7
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Abstract
BACKGROUND Semisynthetic cephalosporins are primarily synthesized from 7-aminocephalosporanic acid (7-ACA), which is usually obtained by chemical deacylation of cephalosporin C (CPC). The chemical production of 7-ACA includes, however, several expensive steps and requires thorough treatment of chemical wastes. Therefore, an enzymatic conversion of CPC to 7-ACA by cephalosporin acylase is of great interest. The biggest obstacle preventing this in industrial production is that cephalosporin acylase uses glutaryl-7ACA as a primary substrate and has low substrate specificity for CPC. RESULTS We have solved the first crystal structure of a cephalosporin acylase from Pseudomonas diminuta at 2.0 A resolution. The overall structure looks like a bowl with two "knobs" consisting of helix- and strand-rich regions, respectively. The active site is mostly formed by the distinctive structural motif of the N-terminal (Ntn) hydrolase superfamily. Superposition of the 61 residue active-site pocket onto that of penicillin G acylase shows an rmsd in Calpha positions of 1.38 A. This indicates structural similarity in the active site between these two enzymes, but their overall structures are elsewhere quite different. CONCLUSION The substrate binding pocket of the P. diminuta cephalosporin acylase provides detailed insight into the ten key residues responsible for the specificity of the cephalosporin C side chain in four classes of cephalosporin acylases, and it thereby forms a basis for the design of an enzyme with an improved conversion rate of CPC to 7-ACA. The structure also provides structural evidence that four of the five different classes of cephalosporin acylases can be grouped into one family of the Ntn hydrolase superfamily.
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Affiliation(s)
- Y Kim
- School of Chemical Engineering Yeungnam University, Kyungsan 712-749, Dae-Dong, South Korea.
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Baca AM, Sirawaraporn R, Turley S, Sirawaraporn W, Hol WG. Crystal structure of Mycobacterium tuberculosis 7,8-dihydropteroate synthase in complex with pterin monophosphate: new insight into the enzymatic mechanism and sulfa-drug action. J Mol Biol 2000; 302:1193-212. [PMID: 11007651 DOI: 10.1006/jmbi.2000.4094] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The enzyme 7,8-dihydropteroate synthase (DHPS) catalyzes the condensation of para-aminobenzoic acid (pABA) with 6-hydroxymethyl-7, 8-dihydropterin-pyrophosphate to form 7,8-dihydropteroate and pyrophosphate. DHPS is essential for the de novo synthesis of folate in prokaryotes, lower eukaryotes, and in plants, but is absent in mammals. Inhibition of this enzyme's activity by sulfonamide and sulfone drugs depletes the folate pool, resulting in growth inhibition and cell death. Here, we report the 1.7 A resolution crystal structure of the binary complex of 6-hydroxymethylpterin monophosphate (PtP) with DHPS from Mycobacterium tuberculosis (Mtb), a pathogen responsible for the death of millions of human beings each year. Comparison to other DHPS structures reveals that the M. tuberculosis DHPS structure is in a unique conformation in which loop 1 closes over the active site. The Mtb DHPS structure hints at a mechanism in which both loops 1 and 2 play important roles in catalysis by shielding the active site from bulk solvent and allowing pyrophosphoryl transfer to occur. A binding mode for pABA, sulfonamides and sulfones is suggested based on: (i) the new conformation of the closed loop 1; (ii) the distribution of dapsone and sulfonamide resistance mutations; (iii) the observed direction of the bond between the 6-methyl carbon atom and the bridging oxygen atom to the alpha-phosphate group in the Mtb DHPS:PtP binary complex; and (iv) the conformation of loop 2 in the Escherichia coli DHPS structure. Finally, the Mtb DHPS structure reveals a highly conserved pterin binding pocket that may be exploited for the design of novel antimycobacterial agents.
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Affiliation(s)
- A M Baca
- Department of Bioengineering and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, USA
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9
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Somasiri A, Wu C, Ellchuk T, Turley S, Roskelley CD. Phosphatidylinositol 3-kinase is required for adherens junction-dependent mammary epithelial cell spheroid formation. Differentiation 2000; 66:116-25. [PMID: 11100902 DOI: 10.1046/j.1432-0436.2000.660206.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Adherens junctions facilitate and maintain epithelial cell-cell adhesion. This is true of mammary epithelial cells, both in two dimensional monolayers and in three-dimensional basement membrane cultures. Using the immortalized, functional mouse mammary epithelial scp2 cell line, we found that pharmacological inhibition of phosphatidylinositol 3-kinase (PI3-kinase) disrupted adherens junctions. In monolayers, this disruption was associated with decreased E-cadherin and beta-catenin at sites of cell-cell contact and decreased association of both proteins with the cytoskeleton. Changes in the distribution of f-actin after PI3-kinase inhibition suggest that this disruption of adherens junctions may be mediated by alterations to the cytoskeleton. In basement membrane cultures, PI3-kinase inhibition reversibly prevented adherens junction-dependent spheroid formation and differentiative milk protein gene expression, both in scp2 cells and in a second mouse mammary epithelial cell line, EpH4. Decreasing the calcium concentration in the culture medium produced similar, although less dramatic, phenotypic effects. These data indicate that adherens junctions contribute, at least in part, to the efficient induction of basement membrane-dependent differentiation of mammary epithelial cells.
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Affiliation(s)
- A Somasiri
- Dept. of Anatomy, University of British Columbia, Vancouver, Canada
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10
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Abstract
Dendritic cells (DCs) developmentally regulate antigen uptake by controlling their endocytic capacity. Immature DCs actively internalize antigen. However, mature DCs are poorly endocytic, functioning instead to present antigens to T cells. We have found that endocytic downregulation reflects a decrease in endocytic activity controlled by Rho family GTPases, especially Cdc42. Blocking Cdc42 function by Toxin B treatment or injection of dominant-negative inhibitors of Cdc42 abrogates endocytosis in immature DCs. In mature DCs, injection of constitutively active Cdc42 or microbial delivery of a Cdc42 nucleotide exchange factor reactivates endocytosis. DCs regulate endogenous levels of Cdc42-GTP with activated Cdc42 detectable only in immature cells. We conclude that DCs developmentally regulate endocytosis at least in part by controlling levels of activated Cdc42.
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Affiliation(s)
- W S Garrett
- Department of Cell Biology, Ludwig Institute for Cancer Research, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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11
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Sieker LC, Holmes M, Le Trong I, Turley S, Liu MY, LeGall J, Stenkamp RE. The 1.9 A crystal structure of the "as isolated" rubrerythrin from Desulfovibrio vulgaris: some surprising results. J Biol Inorg Chem 2000; 5:505-13. [PMID: 10968622 DOI: 10.1007/pl00021450] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Rubrerythrin is a non-heme iron dimeric protein isolated from the sulfate-reducing bacterium Desulfovibrio vulgaris. Each monomer has one mononuclear iron center similar to rubredoxin and one dinuclear metal center similar to hemerythrin or ribonucleotide reductase. The 1.88 A X-ray structure of the "as isolated" molecule and a uranyl heavy atom derivative have been solved by molecular replacement techniques. The resulting model of the native "as isolated" molecule, including 164 water molecules, has been refined giving a final R factor of 0.197 (R(free) = 0.255). The structure has the same general protein fold, domain structure, and dimeric interactions as previously found for rubrerythrin [1, 2], but it also has some interesting undetected differences at the metal centers. The refined model of the protein structure has a cis peptide between residues 78 and 79. The Fe-Cys4 center has a previously undetected strong seventh N-H...S hydrogen bond in addition to the six N-H...S bonds usually found in rubredoxin. The dinuclear metal center has a hexacoordinate Fe atom and a tetracoordinate Zn atom. Each metal is coordinated by a GluXXHis polypeptide chain segment. The Zn atom binds at a site distinctly different from that found in the structure of a diiron rubrerythrin. Difference electron density for the uranyl derivative shows an extremely large peak adjacent to and replacing the Zn atom, indicating that this particular site is capable of binding other atoms. This feature/ability may give rise to some of the confusing activities ascribed to this molecule.
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Affiliation(s)
- L C Sieker
- Department of Biological Structure and Biomolecular Structure Center, University of Washington, Seattle 98195-7420, USA
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12
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Suresh S, Turley S, Opperdoes FR, Michels PA, Hol WG. A potential target enzyme for trypanocidal drugs revealed by the crystal structure of NAD-dependent glycerol-3-phosphate dehydrogenase from Leishmania mexicana. Structure 2000; 8:541-52. [PMID: 10801498 DOI: 10.1016/s0969-2126(00)00135-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND NAD-dependent glycerol-3-phosphate dehydrogenase (GPDH) catalyzes the interconversion of dihydroxyacetone phosphate and L-glycerol-3-phosphate. Although the enzyme has been characterized and cloned from a number of sources, until now no three-dimensional structure has been determined for this enzyme. Although the utility of this enzyme as a drug target against Leishmania mexicana is yet to be established, the critical role played by GPDH in the long slender bloodstream form of the related kinetoplastid Trypanosoma brucei makes it a viable drug target against sleeping sickness. RESULTS The 1.75 A crystal structure of apo GPDH from L. mexicana was determined by multiwavelength anomalous diffraction (MAD) techniques, and used to solve the 2.8 A holo structure in complex with NADH. Each 39 kDa subunit of the dimeric enzyme contains a 189-residue N-terminal NAD-binding domain and a 156-residue C-terminal substrate-binding domain. Significant parts of both domains share structural similarity with plant acetohydroxyacid isomeroreductase. The discovery of extra, fatty-acid like, density buried inside the C-terminal domain indicates a possible post-translational modification with an associated biological function. CONCLUSIONS The crystal structure of GPDH from L. mexicana is the first structure of this enzyme from any source and, in view of the sequence identity of 63%, serves as a valid model for the T. brucei enzyme. The differences between the human and trypanosomal enzymes are extensive, with only 29% sequence identity between the parasite and host enzyme, and support the feasibility of exploiting the NADH-binding site to develop selective inhibitors against trypanosomal GPDH. The structure also offers a plausible explanation for the observed inhibition of the T. brucei enzyme by melarsen oxide, the active form of the trypanocidal drugs melarsoprol and cymelarsan.
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Affiliation(s)
- S Suresh
- Department of Biological Structure, Biomolecular Structure Center, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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13
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AEvarsson A, Chuang JL, Wynn RM, Turley S, Chuang DT, Hol WG. Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease. Structure 2000; 8:277-91. [PMID: 10745006 DOI: 10.1016/s0969-2126(00)00105-2] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Mutations in components of the extraordinarily large alpha-ketoacid dehydrogenase multienzyme complexes can lead to serious and often fatal disorders in humans, including maple syrup urine disease (MSUD). In order to obtain insight into the effect of mutations observed in MSUD patients, we determined the crystal structure of branched-chain alpha-ketoacid dehydrogenase (E1), the 170 kDa alpha(2)beta(2) heterotetrameric E1b component of the branched-chain alpha-ketoacid dehydrogenase multienzyme complex. RESULTS The 2.7 A resolution crystal structure of human E1b revealed essentially the full alpha and beta polypeptide chains of the tightly packed heterotetramer. The position of two important potassium (K(+)) ions was determined. One of these ions assists a loop that is close to the cofactor to adopt the proper conformation. The second is located in the beta subunit near the interface with the small C-terminal domain of the alpha subunit. The known MSUD mutations affect the functioning of E1b by interfering with the cofactor and K(+) sites, the packing of hydrophobic cores, and the precise arrangement of residues at or near several subunit interfaces. The Tyr-->Asn mutation at position 393-alpha occurs very frequently in the US population of Mennonites and is located in a unique extension of the human E1b alpha subunit, contacting the beta' subunit. CONCLUSIONS Essentially all MSUD mutations in human E1b can be explained on the basis of the structure, with the severity of the mutations for the stability and function of the protein correlating well with the severity of the disease for the patients. The suggestion is made that small molecules with high affinity for human E1b might alleviate effects of some of the milder forms of MSUD.
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Affiliation(s)
- A AEvarsson
- Department of Biological Structure, University of Washington School of Medicine, Seattle 98195, USA
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14
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Affiliation(s)
- R M Steinman
- Laboratory of Immunobiology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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15
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Li R, Sirawaraporn R, Chitnumsub P, Sirawaraporn W, Wooden J, Athappilly F, Turley S, Hol WG. Three-dimensional structure of M. tuberculosis dihydrofolate reductase reveals opportunities for the design of novel tuberculosis drugs. J Mol Biol 2000; 295:307-23. [PMID: 10623528 DOI: 10.1006/jmbi.1999.3328] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dihydrofolate reductase (DHFR) catalyzes the NADPH-dependent reduction of dihydrofolate to tetrahydrofolate and is essential for the synthesis of thymidylate, purines and several amino acids. Inhibition of the enzyme's activity leads to arrest of DNA synthesis and cell death. The enzyme has been studied extensively as a drug target for bacterial, protozoal and fungal infections, and also for neoplastic and autoimmune diseases. Here, we report the crystal structure of dihydrofolate reductase from Mycobacterium tuberculosis, a human pathogen responsible for the death of millions of human beings per year. Three crystal structures of ternary complexes of M. tuberculosis DHFR with NADP and different inhibitors have been determined, as well as the binary complex with NADP, with resolutions ranging from 1.7 to 2.0 A. The three DHFR inhibitors are the anticancer drug methotrexate, the antimicrobial trimethoprim and Br-WR99210, an analogue of the antimalarial agent WR99210. Structural comparison of these complexes with human dihydrofolate reductase indicates that the overall protein folds are similar, despite only 26 % sequence identity, but that the environments of both NADP and of the inhibitors contain interesting differences between the enzymes from host and pathogen. Specifically, residues Ala101 and Leu102 near the N6 of NADP are distinctly more hydrophobic in the M. tuberculosis than in the human enzyme. Another striking difference occurs in a region near atoms N1 and N8 of methotrexate, which is also near atom N1 of trimethoprim, and near the N1 and two methyl groups of Br-WR99210. A glycerol molecule binds here in a pocket of the M. tuberculosis DHFR:MTX complex, while this pocket is essentially filled with hydrophobic side-chains in the human enzyme. These differences between the enzymes from pathogen and host provide opportunities for designing new selective inhibitors of M. tuberculosis DHFR.
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Affiliation(s)
- R Li
- Departments of Biological Structure and Biochemistry Biomolecular Structure Center and Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA
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16
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Aevarsson A, Seger K, Turley S, Sokatch JR, Hol WG. Crystal structure of 2-oxoisovalerate and dehydrogenase and the architecture of 2-oxo acid dehydrogenase multienzyme complexes. Nat Struct Biol 1999; 6:785-92. [PMID: 10426958 DOI: 10.1038/11563] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The family of giant multienzyme complexes metabolizing pyruvate, 2-oxoglutarate, branched-chain 2-oxo acids or acetoin contains several of the largest and most sophisticated protein assemblies known, with molecular masses between 4 and 10 million Da. The principal enzyme components, E1, E2 and E3, are present in numerous copies and utilize multiple cofactors to catalyze a directed sequence of reactions via substrate channeling. The crystal structure of a heterotetrameric (alpha2beta2) E1, 2-oxoisovalerate dehydrogenase from Pseudomonas putida, reveals a tightly packed arrangement of the four subunits with the beta2-dimer held between the jaws of a 'vise' formed by the alpha2-dimer. A long hydrophobic channel, suitable to accommodate the E2 lipoyl-lysine arm, leads to the active site, which contains the cofactor thiamin diphosphate (ThDP) and an inhibitor-derived covalent modification of a histidine side chain. The E1 structure, together with previous structural information on E2 and E3, completes the picture of the shared architectural features of these enormous macromolecular assemblies.
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Affiliation(s)
- A Aevarsson
- Departments of Biological Structure and Biochemistry, Biomolecular Structure Center, University of Washington, P.O. Box 357742, Seattle, Washington 98195-7742, USA
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17
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Abstract
Antigen uptake, processing and presentation by dendritic cells [DCs] have become amenable to cell biological approaches. The critical events occur in DCs that are undergoing maturation in response to inflammatory stimuli. Successful antigen presentation can be monitored directly using antibodies that are specific for particular MHC-peptide complexes. What a contrast to earlier times when it was difficult to visualize even the uptake of antigen into isolated DCs and DCs in the T cell areas of lymphoid organs! We emphasize here the efficiency of antigen capture and presentation by maturing DCs, especially for dying cells. This presentation of cellular antigens by DCs likely explains the phenomenon of cross priming in the setting of transplantation and other clinical states.
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Affiliation(s)
- R M Steinman
- Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, NY 10021, USA.
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18
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Sieker LC, Holmes M, Le Trong I, Turley S, Santarsiero BD, Liu MY, LeGall J, Stenkamp RE. Alternative metal-binding sites in rubrerythrin. Nat Struct Biol 1999; 6:308-9. [PMID: 10201393 DOI: 10.1038/7538] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- L C Sieker
- Department of Biological Structure and Biomolecular Structure Center, University of Washington, Seattle 98195-7420, USA
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19
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Inaba K, Turley S, Yamaide F, Iyoda T, Mahnke K, Inaba M, Pack M, Subklewe M, Sauter B, Sheff D, Albert M, Bhardwaj N, Mellman I, Steinman RM. Efficient presentation of phagocytosed cellular fragments on the major histocompatibility complex class II products of dendritic cells. J Exp Med 1998; 188:2163-73. [PMID: 9841929 PMCID: PMC2212389 DOI: 10.1084/jem.188.11.2163] [Citation(s) in RCA: 481] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/1998] [Indexed: 11/07/2022] Open
Abstract
Cells from the bone marrow can present peptides that are derived from tumors, transplants, and self-tissues. Here we describe how dendritic cells (DCs) process phagocytosed cell fragments onto major histocompatibility complex (MHC) class II products with unusual efficacy. This was monitored with the Y-Ae monoclonal antibody that is specific for complexes of I-Ab MHC class II presenting a peptide derived from I-Ealpha. When immature DCs from I-Ab mice were cultured for 5-20 h with activated I-E+ B blasts, either necrotic or apoptotic, the DCs produced the epitope recognized by the Y-Ae monoclonal antibody and stimulated T cells reactive with the same MHC-peptide complex. Antigen transfer was also observed with human cells, where human histocompatibility leukocyte antigen (HLA)-DRalpha includes the same peptide sequence as mouse I-Ealpha. Antigen transfer was preceded by uptake of B cell fragments into MHC class II-rich compartments. Quantitation of the amount of I-E protein in the B cell fragments revealed that phagocytosed I-E was 1-10 thousand times more efficient in generating MHC-peptide complexes than preprocessed I-E peptide. When we injected different I-E- bearing cells into C57BL/6 mice to look for a similar phenomenon in vivo, we found that short-lived migrating DCs could be processed by most of the recipient DCs in the lymph node. The consequence of antigen transfer from migratory DCs to lymph node DCs is not yet known, but we suggest that in the steady state, i.e., in the absence of stimuli for DC maturation, this transfer leads to peripheral tolerance of the T cell repertoire to self.
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Affiliation(s)
- K Inaba
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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20
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Abstract
We have identified two RHAMM (receptor for hyaluronan-mediated motility) isoforms that encode an alternatively spliced exon 4 (Hall, C. L., Yang, B., Yang, X., Zhang, S., Turley, M., Samuel, S., Lange, L. A., Wang, C., Curpen, G. D., Savani, R. C., Greenberg, A. H., and Turley, E. A. (1995) Cell 82, 19-26 and Wang, C., Entwistle, J., Hou, G., Li, Q., and Turley, E. A. (1996) Gene 174, 299-306). One of these, RHAMM variant 4 (RHAMMv4), is transforming when overexpressed and regulates Ras signaling (Hall et al.). Here we note using flow cytometry and confocal analysis that RHAMM isoforms encoding exon 4 occur both on the cell surface and in the cytoplasm. Epitope-tagging experiments indicate that RHAMMv4 occurs only in the cytoplasm. Several observations suggest that both cell surface RHAMM isoforms and RHAMMv4 are involved in regulating extracellular-regulated kinase (ERK) activity. Affinity-purified anti-RHAMM exon 4 antibodies block the ability of platelet-derived growth factor to activate ERK, and these reagents modify the protein tyrosine phosphorylation profile of proteins resulting from treatment with platelet-derived growth factor. A dominant negative form of RHAMMv4 inhibits mutant active Ras activation of ERK and coimmunoprecipitates with both mitogen-activated protein kinase kinase and ERK, suggesting that the intracellular RHAMMv4 acts downstream of Ras, possibly at the level of mitogen-activated protein kinase kinase-ERK interactions. Consistent with this, overexpression of RHAMMv4 constitutively activates ERK. These results identify a novel mechanism for the regulation of the Ras-ERK signaling pathway and suggest that RHAMM plays multiple roles in this regulation.
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Affiliation(s)
- S Zhang
- Hospital for Sick Children, Division of Cardiovascular Research, Toronto, Ontario, Canada M5G1X8
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21
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Abstract
We have defined conditions for generating large numbers of dendritic cells (DC) in marrow cultures from 10-12-week-old ACI or WF rats. The combination of granulocyte-macrophage colony-stimulating factor (GM-CSF) and TNF-alpha, known to induce DC from human CD34+ progenitors, was not effective with rat. In contrast, GM-CSF plus IL-4 generated DC in high yield, corresponding to 30-40% of the initial number of plated marrow cells. The DC proliferated in distinctive aggregates, in which most cells had an immature phenotype marked by undetectable surface B7 and high levels of MHC class II products within intracellular lysosomes. When dislodged and dispersed, the aggregates gave rise to mature stellate DC with abundant surface MHC class II and B7, sparse MHC class II- lysosomes, and strong T cell-stimulating capacity. Therefore, rat marrow progenitors can generate large numbers of immature DC, with abundant intracellular MHC class II compartments, and potent, stimulatory, mature DC.
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Affiliation(s)
- M Talmor
- Department of Surgery, New York Hospital-Cornell Medical Center, New York, USA
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22
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Abstract
We have defined conditions for generating large numbers of dendritic cells (DC) in marrow cultures from 10-12-week-old ACI or WF rats. The combination of granulocyte-macrophage colony-stimulating factor (GM-CSF) and TNF-alpha, known to induce DC from human CD34+ progenitors, was not effective with rat. In contrast, GM-CSF plus IL-4 generated DC in high yield, corresponding to 30-40% of the initial number of plated marrow cells. The DC proliferated in distinctive aggregates, in which most cells had an immature phenotype marked by undetectable surface B7 and high levels of MHC class II products within intracellular lysosomes. When dislodged and dispersed, the aggregates gave rise to mature stellate DC with abundant surface MHC class II and B7, sparse MHC class II- lysosomes, and strong T cell-stimulating capacity. Therefore, rat marrow progenitors can generate large numbers of immature DC, with abundant intracellular MHC class II compartments, and potent, stimulatory, mature DC.
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Affiliation(s)
- M Talmor
- Department of Surgery, New York Hospital-Cornell Medical Center, New York, USA
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23
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Murphy ME, Turley S, Adman ET. Structure of nitrite bound to copper-containing nitrite reductase from Alcaligenes faecalis. Mechanistic implications. J Biol Chem 1997; 272:28455-60. [PMID: 9353305 DOI: 10.1074/jbc.272.45.28455] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The structures of oxidized, reduced, nitrite-soaked oxidized and nitrite-soaked reduced nitrite reductase from Alcaligenes faecalis have been determined at 1.8-2.0 A resolution using data collected at -160 degrees C. The active site at cryogenic temperature, as at room temperature, contains a tetrahedral type II copper site liganded by three histidines and a water molecule. The solvent site is empty when crystals are reduced with ascorbate. A fully occupied oxygen-coordinate nitrite occupies the solvent site in crystals soaked in nitrite. Ascorbate-reduced crystals soaked in a glycerol-methanol solution and nitrite at -40 degrees C remain colorless at -160 degrees C but turn amber-brown when warmed, suggesting that NO is released. Nitrite is found at one-half occupancy. Five new solvent sites in the oxidized nitrite bound form exhibit defined but different occupancies in the other three forms. These results support a previously proposed mechanism by which nitrite is bound primarily by a single oxygen atom that is protonable, and after reduction and cleavage of that N-O bond, NO is released leaving the oxygen atom bound to the Cu site as hydroxide or water.
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Affiliation(s)
- M E Murphy
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington 98195-7420, USA
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24
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Sacca R, Turley S, Soong L, Mellman I, Ruddle NH. Transgenic expression of lymphotoxin restores lymph nodes to lymphotoxin-alpha-deficient mice. The Journal of Immunology 1997. [DOI: 10.4049/jimmunol.159.9.4252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Lymphotoxin-alpha (LT alpha) has recently been demonstrated to be important in the development of lymph nodes (LN), Peyer's patches, and splenic organization, including the development of germinal centers. To elucidate the role of LT alpha in lymphoid organogenesis and the plasticity of the process, we examined LT alpha-/- mice in which an LT alpha transgene under the control of the rat insulin promoter (RIPLT) is expressed in the pancreas, kidney, and skin. The LT alpha transgene restored LN in LT alpha-/- mice. The reconstituted LN of RIPLT.LT alpha-/- mice had germinal center-like peanut agglutinin-positive regions, but lacked follicular dendritic cells. Although the LT alpha transgene did not restore Peyer's patches or splenic architecture, it restored the ability of the spleen to form germinal centers and follicular dendritic cell networks. Lymphocytes isolated from the reconstituted LN showed normal proliferative responses to T and B cell mitogens and were defective in their proliferative response to T-dependent Ag, and a decreased number of interdigitating dendritic cells was apparent in the RIPLT.LT alpha-/- mice LN. Expression of the RIPLT transgene in mice deficient in LT beta did not reconstitute LN, suggesting an important role for LT beta in the mechanisms that reconstitute LN in RIPLT.LT alpha-/- mice. These data are the first to demonstrate reconstitution of LN in LT alpha-/- mice and show that the process of LN restoration is amenable to manipulation with ectopic lymphotoxin.
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Affiliation(s)
- R Sacca
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
| | - S Turley
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
| | - L Soong
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
| | - I Mellman
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
| | - N H Ruddle
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
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25
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Sacca R, Turley S, Soong L, Mellman I, Ruddle NH. Transgenic expression of lymphotoxin restores lymph nodes to lymphotoxin-alpha-deficient mice. J Immunol 1997; 159:4252-60. [PMID: 9379020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Lymphotoxin-alpha (LT alpha) has recently been demonstrated to be important in the development of lymph nodes (LN), Peyer's patches, and splenic organization, including the development of germinal centers. To elucidate the role of LT alpha in lymphoid organogenesis and the plasticity of the process, we examined LT alpha-/- mice in which an LT alpha transgene under the control of the rat insulin promoter (RIPLT) is expressed in the pancreas, kidney, and skin. The LT alpha transgene restored LN in LT alpha-/- mice. The reconstituted LN of RIPLT.LT alpha-/- mice had germinal center-like peanut agglutinin-positive regions, but lacked follicular dendritic cells. Although the LT alpha transgene did not restore Peyer's patches or splenic architecture, it restored the ability of the spleen to form germinal centers and follicular dendritic cell networks. Lymphocytes isolated from the reconstituted LN showed normal proliferative responses to T and B cell mitogens and were defective in their proliferative response to T-dependent Ag, and a decreased number of interdigitating dendritic cells was apparent in the RIPLT.LT alpha-/- mice LN. Expression of the RIPLT transgene in mice deficient in LT beta did not reconstitute LN, suggesting an important role for LT beta in the mechanisms that reconstitute LN in RIPLT.LT alpha-/- mice. These data are the first to demonstrate reconstitution of LN in LT alpha-/- mice and show that the process of LN restoration is amenable to manipulation with ectopic lymphotoxin.
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Affiliation(s)
- R Sacca
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA
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26
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Abstract
This paper outlines the basis for and terms of the European Working Time Directive, and its implementation in the Accident and Emergency (A & E) department of a UK hospital. The author describes how the directive was applied to the existing requirements of staffing the A & E department, including reaching a majority agreement on shift times. The new A & E staffing rota was implemented on 14 May 1997, and initial evaluation, after 6 weeks' running, is given.
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Affiliation(s)
- S Turley
- Northwick Park & St Mark's NHS Trust, Harrow, Middlesex, UK
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27
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Adman ET, Murphy MEP, Turley S, Kukimoto M, Nishiyama M. Oxidized and reduced nitrite reductase with and without nitrite bound. Acta Crystallogr A 1996. [DOI: 10.1107/s0108767396094093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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28
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Peters-Libeu CA, Adman ET, Turley S, Beppu T, Nishiyama M. Tuning the redox potential of an electron-transfer protein: analysis of the high potential P801 pseudoazurin. Acta Crystallogr A 1996. [DOI: 10.1107/s0108767396093749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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29
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Delboni LF, Mande SC, Rentier-Delrue F, Mainfroid V, Turley S, Vellieux FM, Martial JA, Hol WG. Crystal structure of recombinant triosephosphate isomerase from Bacillus stearothermophilus. An analysis of potential thermostability factors in six isomerases with known three-dimensional structures points to the importance of hydrophobic interactions. Protein Sci 1995; 4:2594-604. [PMID: 8580851 PMCID: PMC2143043 DOI: 10.1002/pro.5560041217] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The structure of the thermostable triosephosphate isomerase (TIM) from Bacillus stearothermophilus complexed with the competitive inhibitor 2-phosphoglycolate was determined by X-ray crystallography to a resolution of 2.8 A. The structure was solved by molecular replacement using XPLOR. Twofold averaging and solvent flattening was applied to improve the quality of the map. Active sites in both the subunits are occupied by the inhibitor and the flexible loop adopts the "closed" conformation in either subunit. The crystallographic R-factor is 17.6% with good geometry. The two subunits have an RMS deviation of 0.29 A for 248 C alpha atoms and have average temperature factors of 18.9 and 15.9 A2, respectively. In both subunits, the active site Lys 10 adopts an unusual phi, psi combination. A comparison between the six known thermophilic and mesophilic TIM structures was conducted in order to understand the higher stability of B. stearothermophilus TIM. Although the ratio Arg/(Arg+Lys) is higher in B. stearothermophilus TIM, the structure comparisons do not directly correlate this higher ratio to the better stability of the B. stearothermophilus enzyme. A higher number of prolines contributes to the higher stability of B. stearothermophilus TIM. Analysis of the known TIM sequences points out that the replacement of a structurally crucial asparagine by a histidine at the interface of monomers, thus avoiding the risk of deamidation and thereby introducing a negative charge at the interface, may be one of the factors for adaptability at higher temperatures in the TIM family. Analysis of buried cavities and the areas lining these cavities also contributes to the greater thermal stability of the B. stearothermophilus enzyme. However, the most outstanding result of the structure comparisons appears to point to the hydrophobic stabilization of dimer formation by burying the largest amount of hydrophobic surface area in B. stearothermophilus TIM compared to all five other known TIM structures.
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Affiliation(s)
- L F Delboni
- Department of Biological Structure, School of Medicine, University of Washington, Seattle 98195, USA
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30
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Adman ET, Godden JW, Turley S. The structure of copper-nitrite reductase from Achromobacter cycloclastes at five pH values, with NO2- bound and with type II copper depleted. J Biol Chem 1995; 270:27458-74. [PMID: 7499203 DOI: 10.1074/jbc.270.46.27458] [Citation(s) in RCA: 200] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
High resolution x-ray crystallographic structures of nitrite reductase from Achromobacter cycloclastes, undertaken in order to understand the pH optimum of the reaction with nitrite, show that at pH 5.0, 5.4, 6.0, 6.2, and 6.8, no significant changes occur, other than in the occupancy of the type II copper at the active site. An extensive network of hydrogen bonds, both within and between subunits of the trimer, maintains the rigidity of the protein structure. A water occupies a site approximately 1.5 A from the site of the type II copper in the structure of the type II copper-depleted structure (at pH 5.4), again with no other significant changes in structure. In nitrite-soaked crystals, nitrite binds via its oxygens to the type II copper and replaces the water normally bound to the type II copper. The active-site cavity of the protein is distinctly hydrophobic on one side and hydrophilic on the other, providing a possible path for diffusion of the product NO. Asp-98 exhibits thermal parameter values higher than its surroundings, suggesting a role in shuttling the two protons necessary for the overall reaction. The strong structural homology with cupredoxins is described.
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Affiliation(s)
- E T Adman
- Department of Biological Structure, University of Washington, Seattle 98195-7420, USA
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31
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Murphy ME, Turley S, Kukimoto M, Nishiyama M, Horinouchi S, Sasaki H, Tanokura M, Adman ET. Structure of Alcaligenes faecalis nitrite reductase and a copper site mutant, M150E, that contains zinc. Biochemistry 1995; 34:12107-17. [PMID: 7547950 DOI: 10.1021/bi00038a003] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The structures at 2.0 and 2.25 A resolution of native and recombinant nitrite reductase from Alcaligenes faecalis show that they are identical to each other and very similar to nitrite reductase from Achromobacter cycloclastes. The crystallographic structure of a mutant, M150E, which unlike the wild-type protein cannot be reduced by pseudoazurin, shows that the glutamate replacement for methionine binds to a metal at the type I Cu site via only one oxygen. Anomalous scattering data collected at wavelengths of 1.040 and 1.377 A reveal that the metal at the type I site is a Zn. No significant differences from the native structure other than local perturbations at the type I site are seen. A local pseudo 2-fold axis relates the two domains of different monomers which form the active site. The two residues, Asp98 and His255, believed to be involved in catalysis are related by this 2-fold. An unusual (+)-(+) charge interaction between Lys269, Glu279, and His100 helps to orient the active site Cu ligand, His100. A number of negatively charged surface residues create an electrostatic field whose shape suggests that it may serve to direct incoming negatively charged nitrite as well as to dock the electron donor partner, pseudoazurin.
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Affiliation(s)
- M E Murphy
- Department of Biological Structure, School of Medicine, University of Washington, Seattle 98195-7420, USA
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32
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Kukimoto M, Nishiyama M, Ohnuki T, Turley S, Adman ET, Horinouchi S, Beppu T. Identification of interaction site of pseudoazurin with its redox partner, copper-containing nitrite reductase from Alcaligenes faecalis S-6. Protein Eng 1995; 8:153-8. [PMID: 7630886 DOI: 10.1093/protein/8.2.153] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pseudoazurin, a low molecular weight protein containing a single type I copper, functions as an electron donor to a copper-containing nitrite reductase (NIR) in a denitrifying bacterium Alcaligenes faecalis S-6. To elucidate the protein-protein interaction between these two copper-containing proteins, each of nine out of 13 lysine residues on the surface of pseudoazurin were independently replaced by alanine or aspartate, and the effects of the mutations on the interaction with NIR, as well as the physicochemical properties of pseudoazurin, were analyzed. All of the mutated pseudoazurins showed optical spectra and oxidation-reduction potentials almost identical to those of wild-type pseudoazurin, suggesting that none of the replacements of these lysine residues affected the environment around the type I copper site. Kinetic analysis of electron transfer between mutated pseudoazurins and NIR reveals that the lysine mutations have very little effect on the rate of electron transfer to NIR, but substitution at residues 10, 38, 57 and 77, all close to the copper site, substantially decreases the affinity of pseudoazurin for NIR. This suggests that pseudoazurin interacts with NIR through the region close to the type I copper site. The refined X-ray structures of Lys38Asp and Lys10Asp/Lys38Asp show that the molecular structure has indeed changed little. A new space group is observed for the Lys109Ala mutant crystal. Crystal packing interactions change for the Lys10Asp/Lys38Asp mutant but remain the same for Lys38Asp and Lys59Ala mutants.
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Affiliation(s)
- M Kukimoto
- Department of Biotechnology, University of Tokyo, Japan
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33
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Kukimoto M, Nishiyama M, Murphy ME, Turley S, Adman ET, Horinouchi S, Beppu T. X-ray structure and site-directed mutagenesis of a nitrite reductase from Alcaligenes faecalis S-6: roles of two copper atoms in nitrite reduction. Biochemistry 1994; 33:5246-52. [PMID: 8172899 DOI: 10.1021/bi00183a030] [Citation(s) in RCA: 147] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nitrite reductase (NIR) from the denitrifying bacterium Alcaligenes faecalis S-6 is a copper-containing enzyme which requires pseudoazurin, a low molecular weight protein containing a single type I copper atom, as a direct electron donor in vivo. Crystallographic analysis shows that NIR is a trimer composed of three identical subunits, each of which contains one atom of type I copper and one atom of type II copper, and that the ligands to the type I and type II copper atoms are the same as those of the Achromobacter cycloclastes NIR. An efficient NIR expression-secretion system in Escherichia coli was constructed and used for site-directed mutagenesis. An NIR mutant with a replacement of the type II copper ligand, His135, by Lys still retained a type II copper site as well as a type I copper atom, but it completely lost nitrite-reducing activity as measured with methyl viologen as an electron donor. On the other hand, another mutant with a replacement of the type I copper ligand, Met150, by Glu contained only a type II copper atom, but it still retained significant nitrite-reducing activity with methyl viologen. When pseudoazurin was used as an electron donor for the reaction, however, Met150Glu failed to catalyze the reduction of nitrite. Kinetic analysis of the electron transfer between NIR and pseudoazurin revealed that the electron-transfer rate between Met150Glu and pseudoazurin was reduced 1000-fold relative to that of wild-type NIR.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Kukimoto
- Department of Agricultural Chemistry, Faculty of Agriculture, University of Tokyo, Japan
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34
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Adman ET, Turley S. Domain interactions and the type II Cu active site in nitrite reductase. Acta Crystallogr A 1993. [DOI: 10.1107/s0108767378097834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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35
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Merrit E, Sixma TK, van den Akker F, Sarfaty S, Turley S, Kalk KH, Feil I, Hol WGJ. Three-dimensional structure of choleratoxin's B pentamer in complex with its pentasaccharide receptor and comparison with the structure of the related entertoxin from E.coli. Acta Crystallogr A 1993. [DOI: 10.1107/s0108767378097275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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36
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Hendle J, Mattevi A, Obmolova G, Sarfaty S, Kalk KH, Turley S, Hol WGJ. Towards the atomic structure of 2-oxo acid dehydrogenase multi-enzyme complexes. Acta Crystallogr A 1993. [DOI: 10.1107/s0108767378097718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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37
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Merritt EA, Stout GH, Turley S, Sieker LC, Jehsen LH, Orme-Johnson WH. Structure at pH 6.5 of ferredoxin I from Azotobacter vinelandii at 2.3 Å resolution. Acta Crystallogr D Biol Crystallogr 1993; 49:272-81. [PMID: 15299532 DOI: 10.1107/s0907444992007248] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Ferredoxin I from Azotobacter vinelandii (AvFdI) is an iron-sulfur protein composed of 106 amino acids, seven Fe atoms and eight inorganic S* atoms. A crystallographic redetermination of its structure showed the originally reported structure to be incorrect. We report here the crystal structure of AvFdI at pH 6.5. Extensive refinement has led to a final R value of 0.170 for all 6986 non-extinct reflections in the range 10-2.3 A using a solvent model which includes 98 discrete solvent atoms with occupancies between 0.3 and 1.0 and an average B value of 22.5 A(2). The first half of the peptide chain closely resembles that of the 55-residue ferredoxin from Peptococcus aerogenes (PaFd), while the remainder consists of three turns of helix and a series of loops which form a cap over part of the molecular core. Despite the similarities in structure and surroundings, the corresponding 4Fe4S* clusters in PaFd and AvFdI have strikingly different redox potentials; a possible explanation has been sought in the differing hydration models for the two molecules.
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Affiliation(s)
- E A Merritt
- Department of Biological Structure, University of Washington, Seattle 98195, USA
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38
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Nishiyama M, Suzuki J, Ohnuki T, Chang HC, Horinouchi S, Turley S, Adman ET, Beppu T. Site-directed mutagenesis of pseudoazurin from Alcaligenes faecalis S-6; Pro80Ala mutant exhibits marked increase in reduction potential. Protein Eng 1992; 5:177-84. [PMID: 1594573 DOI: 10.1093/protein/5.2.177] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pseudoazurin (a blue copper protein or cupredoxin) of a denitrifying bacterium Alcaligenes faecalis S-6 is a direct electron carrier for a Cu-containing nitrite reductase (NIR) of the same organism. Site-directed mutagenesis of the pseudoazurin was carried out using an Escherichia coli expression system. Replacement of Tyr74 by Phe to remove an internal hydrogen bond in the beta-barrel caused a slight decrease in heat stability as well as a requirement for a higher concentration of Cu2+ for production in the E. coli host. Exchange of Ala for Pro80 adjacent to His81, one of the four ligands binding a type I Cu atom, caused a marked increase in reduction potential by 139 mV without change in the optical absorption spectrum. The ability of the pseudoazurin to transfer electrons to NIR was markedly diminished but the apparent Km of NIR for pseudoazurin was not affected by the mutation. X-ray diffraction data collected on the oxidized and reduced forms of the Pro80Ala mutant show that a water molecule occupies the pocket created by the absent side chain. This observation suggests that the increase in reduction potential may be caused due to the increased solvent accessibility to the Cu atom. The electron density difference maps on these structures (at 2.0 A) show that this water moves during the change in oxidation state, and that there are small, but localized, conformational changes greater than 6.5 A from the copper site, as well as movement of both the Cu2+ and the cysteinate sulfur.
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Affiliation(s)
- M Nishiyama
- Department of Agricultural Chemistry, University of Tokyo, Japan
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39
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Godden JW, Turley S, Teller DC, Adman ET, Liu MY, Payne WJ, LeGall J. The 2.3 angstrom X-ray structure of nitrite reductase from Achromobacter cycloclastes. Science 1991; 253:438-42. [PMID: 1862344 DOI: 10.1126/science.1862344] [Citation(s) in RCA: 293] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The three-dimensional crystal structure of the copper-containing nitrite reductase (NIR) from Achromobacter cycloclastes has been determined to 2.3 angstrom (A) resolution by isomorphous replacement. The monomer has two Greek key beta-barrel domains similar to that of plastocyanin and contains two copper sites. The enzyme is a trimer both in the crystal and in solution. The two copper atoms in the monomer comprise one type I copper site (Cu-I; two His, one Cys, and one Met ligands) and one putative type II copper site (Cu-II; three His and one solvent ligands). Although ligated by adjacent amino acids Cu-I and Cu-II are approximately 12.5 A apart. Cu-II is bound with nearly perfect tetrahedral geometry by residues not within a single monomer, but from each of two monomers of the trimer. The Cu-II site is at the bottom of a 12 A deep solvent channel and is the site to which the substrate (NO2-) binds, as evidenced by difference density maps of substrate-soaked and native crystals.
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Affiliation(s)
- J W Godden
- Department of Biochemistry, University of Washington, Seattle 98195
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40
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Abstract
The crystallographic structure analyses of deoxy and oxy hemerythrin have been carried out at 2.0 A resolution to extend the low resolution views of the physiological forms of this oxygen-binding protein. Restrained least-squares refinement has produced molecular models giving R-values of 16.8% for deoxy (41,064 reflections from 10 A to 2.0 A) and 17.3% for oxy hemerythrin (40,413 reflections from 10.0 A to 2.0 A). The protein structure in each derivative is very similar to that of myohemerythrin and the various met forms of hemerythrin. The binuclear complex in each derivative retains an oxygen atom bridging the two iron atoms, but the bond lengths found in deoxy hemerythrin support the idea that, in that form, the bridge is protonated, i.e. the bridging group is a hydroxyl. Dioxygen binds to the pentaco-ordinate iron atom in deoxy hemerythrin in the conversion to oxy hemerythrin. The interatomic distances are consistent with the proposed mechanism where the proton from the bridging group is transferred to the bound dioxygen, stabilizing it in the peroxo oxidation state by forming a hydrogen bond between the peroxy group and the bridging oxygen atom.
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Affiliation(s)
- M A Holmes
- Department of Biological Structure, University of Washington, Seattle 98195
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41
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Adman ET, Turley S, Bramson R, Petratos K, Banner D, Tsernoglou D, Beppu T, Watanabe H. A 2.0-A structure of the blue copper protein (cupredoxin) from Alcaligenes faecalis S-6. J Biol Chem 1989; 264:87-99. [PMID: 2909547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The structure of a blue copper protein, cupredoxin, from the potent denitrifying bacterium Alcaligenes faecalis S-6, has been determined and refined against 2 A x-ray diffraction data. The agreement between observed and calculated structure factors is 0.159, and estimated errors in coordinates are 0.09-0.15 A. The protein folds in a beta sandwich similar to plastocyanin and azurin and includes features such as a "kink" and a "tyrosine loop" which have been noted previously for these proteins as well as immunoglobulins. The copper is bound by four ligands, in a distorted tetrahedral arrangement, with Cu-S gamma = 2.07 A (Cys-78), Cu-N delta 1 = 2.10 and 2.21 for His-40 and His-81, and Cu-S delta = 2.69 A (Met-86). Two of the ligands are further oriented by hydrogen bonds either to other side chains (Asn-9 to His-40), backbone atoms (NH...S) or a water molecule (to His-40). The methionine ligand has no extra constraints. The C-terminal loop containing three of the ligands is hydrogen-bonded to the strand containing His-40 by hydrogen bonds between the conserved residues Thr-79 and Asn-41. The pronounced dichroism of the crystal is a result of the orientation of the normal to the C beta-S gamma-Cu plane parallel to the crystallographic 6-fold axis.
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Affiliation(s)
- E T Adman
- Department of Biological Structure, University of Washington, Seattle 98115
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42
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Sieker LC, Turley S, Le Trong I, Stenkamp RE, Weller PF, Ackerman SJ. Crystallographic characterization of human eosinophil Charcot-Leyden crystals. J Mol Biol 1988; 204:489-91. [PMID: 3221396 DOI: 10.1016/0022-2836(88)90590-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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43
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Abstract
Crystals of a green copper-containing nitrite reductase from Achromobacter cycloclastes, which diffract to high resolution, belong to the cubic space group P213, with a = b = c = 98.4 A. Crystals of a nitrite reductase from Alcaligenes faecalis S-6 have been made, and belong to space group P212121, with a = 77.3 A, b = 94.6 A and c = 141 A. Crystals of the blue copper protein from Ac. cycloclastes have also been obtained: these belong to space group P21212, with cell dimensions a = 34.9 A, b = 91.1 A and c = 36.7 A (1 A = 0.1 nm).
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Affiliation(s)
- S Turley
- Department of Biological Structure, University of Washington, Seattle 98195
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44
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Kissinger CR, Turley S, Clark JI. Structure of WF-3681, 3-(2,5-dihydro-4-hydroxy-5-oxo-3-phenyl-2-furyl)propionic acid. Acta Crystallogr C 1988; 44 ( Pt 3):512-4. [PMID: 3152105 DOI: 10.1107/s010827018700845x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
C13H12O5, Mr = 248.24, monoclinic, C2/c, a = 18.757 (8), b = 7.282 (2), c = 17.511 (8) A, beta = 91.20 (3) degrees, V = 2391 (3) A3, Z = 8, Dx = 1.379 Mg m-3, lambda(Cu K alpha) = 1.54178 A, mu = 0.859 mm-1, F(000) = 1040, T = 293 K. Final R = 0.054 for 1409 unique observed reflections. The molecule contains two planar regions which differ in orientation by 5.7 degrees. Distances from the carbonyl carbons to the center of the phenyl ring are not in the range found in the crystal structures of other potent aldose reductase inhibitor molecules.
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Affiliation(s)
- C R Kissinger
- Department of Biological Structure, University of Washington, Seattle 98195
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45
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Abstract
The structure of Azotobacter vinelandii ferredoxin I (Av FdI, 106 amino acids) has been redetermined, based on x-ray diffraction data from tetragonal crystals of the native protein and two heavy atom derivatives. The current model differs greatly from the one previously reported and is in agreement with arguments based on various spectroscopic and other methods. The unit cell parameters are a = b = 55.62 A and c = 95.51 A, whereas the space group was found to be P4(1)2(1)2 instead of P4(3)2(1)2. The sequence of the first half of Av FdI is closely homologous with ferredoxin from Peptococcus aerogenes (Pa Fd, 54 amino acids) and the fold of the corresponding chain is almost identical. The ligands of the 3Fe complex are Cys-8, -16, and -49, corresponding to three of the four ligands in complex I of Pa Fd; the ligands of the 4Fe complex are Cys-20, -39, -42, and -45, corresponding to the four ligands in complex II of Pa Fd.
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Affiliation(s)
- G H Stout
- Department of Biological Structure, University of Washington School of Medicine 98195
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46
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Sieker LC, Turley S, Prickril BC, LeGall J. Crystallization and preliminary X-ray diffraction study of a protein with a high potential rubredoxin center and a hemerythrin-type Fe center. Proteins 1988; 3:184-6. [PMID: 3255104 DOI: 10.1002/prot.340030306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A newly discovered iron-containing protein, isolated from the bacterium Desulfovibrio vulgaris (Hildenborough, NCIB 8303), has been crystallized. The molecule appears to be a dimer of mass 44kDa. This protein has iron centers with spectrascopic similarities to those in rubredoxins and in hemerythrins. The X-ray diffraction shows symmetry consistent with space group I222 or I212121. Cell parameters are a = 49.2 A, b = 81.3 A, c = 100.1 A, and alpha, beta, gamma = 90 degrees. X-ray diffraction data have been collected to 3.0 A, and a search for useful heavy atom derivatives is in progress for the analysis of the crystal structure of this Fe-protein.
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Affiliation(s)
- L C Sieker
- Department of Biological Structure, University of Washington, Seattle 98195
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47
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Adman ET, Turley S, Sieker LC, LeGall J. Crystallization of a copper-containing nitrite reductase. Acta Crystallogr A 1987. [DOI: 10.1107/s010876738708499x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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