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Lee CD, Rizvi A, McBride SM. KipOTIA detoxifies 5-oxoproline and promotes the growth of Clostridioides difficile. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.01.592088. [PMID: 38746432 PMCID: PMC11092664 DOI: 10.1101/2024.05.01.592088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Clostridioides difficile is an anaerobic enteric pathogen that disseminates in the environment as a dormant spore. For C. difficile and other sporulating bacteria, the initiation of sporulation is a regulated process that prevents spore formation under favorable growth conditions. In Bacillus subtilis , one such mechanism for preventing sporulation is the Kinase Inhibitory Protein, KipI, which impedes activation of the main sporulation kinase. In addition, KipI functions as part of a complex that detoxifies the intermediate metabolite, 5-oxoproline (OP), a harmful by-product of glutamic acid. In this study, we investigate the orthologous Kip proteins in C. difficile to determine their roles in the regulation of sporulation and metabolism. Using deletion mutants in kipIA and the full kipOTIA operon, we show that unlike in B. subtilis, the Kip proteins have no significant impact on sporulation. However, we found that the kip operon encodes a functional oxoprolinase that facilitates detoxification of OP. Further, our data demonstrate that KipOTIA not only detoxifies OP, but also allows OP to be used as a nutrient source that supports the robust growth of C. difficile , thereby facilitating the conversion of a toxic byproduct of metabolism into an effective energy source.
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Roth S, Gandomkar S, Rossi F, Hall M. Mild hydrolysis of chemically stable valerolactams by a biocatalytic ATP-dependent system fueled by metaphosphate. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2024; 26:4498-4505. [PMID: 38654979 PMCID: PMC11033972 DOI: 10.1039/d3gc04434c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 12/07/2023] [Indexed: 04/26/2024]
Abstract
Medium-sized 5- and 6-membered ring lactams are molecules with remarkable stability, in contrast to smaller β-lactams. As monomers, they grant access to nylon-4 and nylon-5, which are alternative polyamides to widespread caprolactam-based nylon-6. Chemical hydrolysis of monocyclic γ- and δ-lactams to the corresponding amino acids requires harsh reaction conditions and up to now, no mild (enzymatic) protocol has been reported. Herein, the biocatalytic potential of a pair of heterologously expressed bacterial ATP-dependent oxoprolinases - OplA and OplB - was exploited. Strong activity in the presence of excess of ATP was monitored on δ-valerolactam and derivatives thereof, while trace activity was detected on γ-butyrolactam. An ATP recycling system based on cheap Graham's salt (sodium metaphosphate) and a polyphosphate kinase allowed the use of catalytic amounts of ATP, leading to up to full conversion of 10 mM δ-valerolactam at 30 °C in aqueous medium. Further improvements were obtained by co-expressing OplA and OplB using the pETDuet1 vector, a strategy which enhanced the soluble expression yield and the protein stability. Finally, a range of phosphodonors was investigated in place of ATP. With acetyl phosphate and carbamoyl phosphate, turnover numbers up to 176 were reached, providing hints on a possible mechanism, which was studied by 31P-NMR.
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Affiliation(s)
- Sebastian Roth
- Institute of Chemistry, University of Graz Heinrichstrasse 28 8010 Graz Austria
| | - Somayyeh Gandomkar
- Institute of Chemistry, University of Graz Heinrichstrasse 28 8010 Graz Austria
| | - Federico Rossi
- Institute of Chemistry, University of Graz Heinrichstrasse 28 8010 Graz Austria
| | - Mélanie Hall
- Institute of Chemistry, University of Graz Heinrichstrasse 28 8010 Graz Austria
- BioHealth, University of Graz Heinrichstrasse 28 8010 Graz Austria
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Oke M, Oni O, Bello R, Samuel-Omoyajowo K, Senbadejo T. Structure-function relationships of the 5-oxoprolinase subunit A: Guiding biological sciences students down the path less traveled. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 47:620-631. [PMID: 31520514 DOI: 10.1002/bmb.21300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 08/02/2019] [Accepted: 08/22/2019] [Indexed: 06/10/2023]
Abstract
Bioinformatics was recently introduced as a module for both undergraduate and postgraduate biological sciences students at our institution. Our experience shows that inquiry-based hands-on exercises provide the most efficient approach to bioinformatic straining. In this article, we report a structural bioinformatics project carried out by Master degree students to determine structure-function relationships of the uncharacterized prokaryotic 5-oxoprolinase subunit A (PxpA). PxpA associates with the PxpBC complex to form a functional 5-oxoprolinase enzyme for conversion of 5-oxoproline to L-glutamate. Although the exact role of PxpA is yet to be determined, it has been demonstrated that PxpBC catalyses the first step of the reaction, which is phosphorylation of 5-oxoproline. Here, we provide evidence that PxpA is involved in the last two steps of the reaction:decyclization of the labile phosphorylated 5-oxoproline to the equally labile γ-glutamylphosphate, and subsequent dephosphorylation to L-glutamate. Structural bioinformatics analysis of four putative PxpA structures revealed that PxpA adopts a non-canonical TIM barrel fold with well-characterized TIM barrel enzyme features. These include a C-terminal groove comprising potentially essential conserved amino acid residues organized into putative motifs. Phylogenetic analysis suggests a relationship between taxonomic grouping and PxpA oligomerization. PxpA forms a tunnel upon ligand binding, thus suggesting that the PxpABC complex employs the mechanism of substrate channeling to protect labile intermediates. Ultimately, students were able to form a testable hypothesis on the function of PxpA, an achievement we consider encouraging other students to emulate. © 2019 International Union of Biochemistry and Molecular Biology, 47(6):620-631, 2019.
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Affiliation(s)
- Muse Oke
- Department of Biological Sciences, Fountain University, Osogbo, Nigeria
| | - Omobukola Oni
- Department of Chemical Sciences, Fountain University, Osogbo, Nigeria
| | - Ronke Bello
- Department of Chemical Sciences, Fountain University, Osogbo, Nigeria
| | | | - Tosin Senbadejo
- Department of Biological Sciences, Fountain University, Osogbo, Nigeria
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Otzen M, Palacio C, Janssen DB. Characterization of the caprolactam degradation pathway in Pseudomonas jessenii using mass spectrometry-based proteomics. Appl Microbiol Biotechnol 2018; 102:6699-6711. [PMID: 29850960 PMCID: PMC6061476 DOI: 10.1007/s00253-018-9073-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 03/21/2018] [Accepted: 03/23/2018] [Indexed: 01/04/2023]
Abstract
Some bacterial cultures are capable of growth on caprolactam as sole carbon and nitrogen source, but the enzymes of the catabolic pathway have not been described. We isolated a caprolactam-degrading strain of Pseudomonas jessenii from soil and identified proteins and genes putatively involved in caprolactam metabolism using quantitative mass spectrometry-based proteomics. This led to the discovery of a caprolactamase and an aminotransferase that are involved in the initial steps of caprolactam conversion. Additionally, various proteins were identified that likely are involved in later steps of the pathway. The caprolactamase consists of two subunits and demonstrated high sequence identity to the 5-oxoprolinases. Escherichia coli cells expressing this caprolactamase did not convert 5-oxoproline but were able to hydrolyze caprolactam to form 6-aminocaproic acid in an ATP-dependent manner. Characterization of the aminotransferase revealed that the enzyme deaminates 6-aminocaproic acid to produce 6-oxohexanoate with pyruvate as amino acceptor. The amino acid sequence of the aminotransferase showed high similarity to subgroup II ω-aminotransferases of the PLP-fold type I proteins. Finally, analyses of the genome sequence revealed the presence of a caprolactam catabolism gene cluster comprising a set of genes involved in the conversion of caprolactam to adipate.
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Affiliation(s)
- Marleen Otzen
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Cyntia Palacio
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Dick B Janssen
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
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5
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Niehaus TD, Elbadawi-Sidhu M, de Crécy-Lagard V, Fiehn O, Hanson AD. Discovery of a widespread prokaryotic 5-oxoprolinase that was hiding in plain sight. J Biol Chem 2017; 292:16360-16367. [PMID: 28830929 DOI: 10.1074/jbc.m117.805028] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/18/2017] [Indexed: 11/06/2022] Open
Abstract
5-Oxoproline (OP) is well-known as an enzymatic intermediate in the eukaryotic γ-glutamyl cycle, but it is also an unavoidable damage product formed spontaneously from glutamine and other sources. Eukaryotes metabolize OP via an ATP-dependent 5-oxoprolinase; most prokaryotes lack homologs of this enzyme (and the γ-glutamyl cycle) but are predicted to have some way to dispose of OP if its spontaneous formation in vivo is significant. Comparative analysis of prokaryotic genomes showed that the gene encoding pyroglutamyl peptidase, which removes N-terminal OP residues, clusters in diverse genomes with genes specifying homologs of a fungal lactamase (renamed prokaryotic 5-oxoprolinase A, pxpA) and homologs of allophanate hydrolase subunits (renamed pxpB and pxpC). Inactivation of Bacillus subtilis pxpA, pxpB, or pxpC genes slowed growth, caused OP accumulation in cells and medium, and prevented use of OP as a nitrogen source. Assays of cell lysates showed that ATP-dependent 5-oxoprolinase activity disappeared when pxpA, pxpB, or pxpC was inactivated. 5-Oxoprolinase activity could be reconstituted in vitro by mixing recombinant B. subtilis PxpA, PxpB, and PxpC proteins. In addition, overexpressing Escherichia coli pxpABC genes in E. coli increased 5-oxoprolinase activity in lysates ≥1700-fold. This work shows that OP is a major universal metabolite damage product and that OP disposal systems are common in all domains of life. Furthermore, it illustrates how easily metabolite damage and damage-control systems can be overlooked, even for central metabolites in model organisms.
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Affiliation(s)
- Thomas D Niehaus
- From the Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611,
| | - Mona Elbadawi-Sidhu
- the West Coast Metabolomics Center, University of California Davis, Davis, California 95616, and
| | - Valérie de Crécy-Lagard
- the Microbiology and Cell Science Department, University of Florida, Gainesville, Florida 32611
| | - Oliver Fiehn
- the West Coast Metabolomics Center, University of California Davis, Davis, California 95616, and
| | - Andrew D Hanson
- From the Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611,
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6
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Nishimura A, Oyama H, Hamada T, Nobuoka K, Shin T, Murao S, Oda K. Molecular cloning, sequencing, and expression in Escherichia coli of the gene encoding a novel 5-oxoprolinase without ATP-hydrolyzing activity from Alcaligenes faecalis N-38A. Appl Environ Microbiol 2000; 66:3201-5. [PMID: 10919770 PMCID: PMC92134 DOI: 10.1128/aem.66.8.3201-3205.2000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The gene encoding a novel 5-oxoprolinase without ATP-hydrolyzing activity from Alcaligenes faecalis N-38A was cloned and characterized. The coding region of this gene is 1,299 bp long. The predicted primary protein is composed of 433 amino acid residues, with a 31-amino-acid signal peptide. The mature protein is composed of 402 amino acid residues with a molecular mass of 46,163 Da. The derived amino acid sequence of the enzyme showed no significant sequence similarity to any other proteins reported so far. The 5-oxoprolinase gene was expressed in Escherichia coli by using a regulatory expression system with an isopropyl-beta-D-thiogalactopyranoside-inducible tac promoter, and its expression level was approximately 16 mg per liter. The purified enzyme has the same characteristics as the authentic enzyme, except for the amino terminus, which has three additional amino acids. The enzyme was markedly inhibited by p-chloromercuribenzoic acid, EDTA, o-phenanthroline, HgCl(2), and CuSO(4). The EDTA-inactivated enzyme was completely restored by the addition of Zn(2+) or Co(2+). In addition, the enzyme was found to contain 1 g-atom of zinc per mol of protein. These results suggest that the 5-oxoprolinase produced by A. faecalis N-38A is a zinc metalloenzyme.
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Affiliation(s)
- A Nishimura
- Department of Applied Biology, Faculty of Textile Science, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Japan
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7
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Nishimura A, Ozaki Y, Oyama H, Shin T, Murao S. Purification and characterization of a novel 5-oxoprolinase (without ATP-hydrolyzing activity) from Alcaligenes faecalis N-38A. Appl Environ Microbiol 1999; 65:712-7. [PMID: 9925605 PMCID: PMC91084 DOI: 10.1128/aem.65.2.712-717.1999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel type of 5-oxoprolinase was found in a cell extract of strain N-38A, which was later identified as Alcaligenes faecalis. The enzyme in the cell extract was purified to a homogeneous state with a yield of 16.6%. The molecular weight of the purified enzyme was estimated to be 47,000 by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, suggesting that the enzyme is a monomeric protein. The enzyme specifically catalyzed a decyclization of L-pyroglutamate without hydrolyzing ATP and also without any requirements for metal ions such as Mg2+ and K+. The optimal pH for the decyclization was 7.4. The reaction was reversible. The equilibrium constant of the reaction, Keq = [L-glutamate]/[L-pyroglutamate], was evaluated to be approximately 0. 035, which indicates that the reaction tends to form L-pyroglutamate. The amino-terminal amino acid sequence of the enzyme was H-Glu-Pro-Arg-Leu-Asp-Thr-Ser-Gln-Leu-Tyr-Ala-Asp-Val-His-Phe-. No protein with a similar sequence was found in the DNASIS database. Based on these data, it was strongly suggested that the enzyme described here is a novel type of 5-oxoprolinase.
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Affiliation(s)
- A Nishimura
- Department of Applied Microbial Technology, The Kumamoto Institute of Technology, Ikeda 4-22-1, Kumamoto 860-0082, Japan
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8
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Ye GJ, Breslow EB, Meister A, Guo-jie GE. The amino acid sequence of rat kidney 5-oxo-L-prolinase determined by cDNA cloning. J Biol Chem 1996; 271:32293-300. [PMID: 8943290 DOI: 10.1074/jbc.271.50.32293] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
5-Oxoprolinase (EC 3.5.2) catalyzes a reaction in which the endergonic cleavage of 5-oxo-L-proline to form L-glutamate is coupled to the exergonic hydrolysis of ATP to ADP and inorganic phosphate. Highly purified preparations of the enzyme have been obtained from rat kidney and Pseudomonas putida. The rat kidney enzyme is composed of two strongly interacting, apparently identical subunits (Mr = 142,000), whereas that from P. putida is composed of two functionally different protein components that can readily be dissociated. Here we report the cloning of rat kidney 5-oxoprolinase with preliminary expression studies. cDNA clones encoding the enzyme were isolated by screening a lambdagt11 cDNA library beginning with a degenerate oligonucleotide probe based on peptide sequence data obtained from the purified enzyme. The whole cDNA clone was completed by amplifying its 5' end from a premade library of rat kidney Marathon-ReadyTM cDNAs using polymerase chain reaction methodology. The composite cDNA (4,016 bases) revealed an uninterrupted open reading frame encoding 1,288 amino acid residues (Mr = 137,759). The deduced amino acid sequence contains all four of the peptide sequences that were independently found in peptide fragments derived from the enzyme. Expression of the full-length clone in Escherichia coli yielded a product of the same size as the rat kidney enzyme and which reacted with antibodies directed against the rat kidney enzyme. The predicted amino acid sequence is almost 50% identical throughout its entire length to that of a hypothetical yeast protein YKL215C. It is also 26% identical in half its length to the bacterial hydantoinase HyuA and 26% identical in the other half to the bacterial hydantoinase HyuB. The results suggest unexpected evolutionary relationships among the hydantoinases and rat kidney 5-oxoprolinase which share the common property of hydrolyzing the imide bond of 5-membered rings but which do not all require ATP.
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Affiliation(s)
- G J Ye
- Department of Biochemistry, Cornell University Medical College, New York, New York 10021, USA
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9
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Ogawa J, Kim JM, Nirdnoy W, Amano Y, Yamada H, Shimizu S. Purification and characterization of an ATP-dependent amidohydrolase, N-methylhydantoin amidohydrolase, from Pseudomonas putida 77. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 229:284-90. [PMID: 7744042 DOI: 10.1111/j.1432-1033.1995.0284l.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
N-Methylhydantoin amidohydrolase, an ATP-dependent amidohydrolase involved in microbial degradation of creatinine, was purified 70-fold to homogeneity, with a 62% overall recovery, and was crystallized from Pseudomonas putida 77. The enzyme has a relative molecular mass of 300,000. It is a tetramer of two identical small subunits (M(r) 70,000) and two identical large subunits (M(r) 80,000). The enzyme requires ATP for the amidohydrolysis of N-methylhydantoin and vice versa. Mg2+, Mn2+ or Co2+, and K+, NH4+, Rb+ or Cs+, were absolutely required concomitantly for the enzyme activity as divalent and monovalent cations, respectively. The Km and Vmax values for N-methylhydantoin were 32 microM and 9.0 mumol.min-1.mg protein-1. The hydrolysis of amide compounds and coupled hydrolysis of ATP were observed with hydantoin, DL-5-methylhydantoin, glutarimide and succimide in addition to N-methylhydantoin. 2-Pyrrolidone, 2-oxazolidone, delta-valerolactam, 2,4-thiazolidinedione, 2-imidazolidone, D-5-oxoproline methyl ester, DL-5-oxoproline methyl ester, and naturally occurring pyrimidine compounds, i.e. dihydrouracil, dihydrothymine, uracil, and thymine, effectively stimulated ATP hydrolysis by the enzyme without undergoing detectable self-hydrolysis.
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Affiliation(s)
- J Ogawa
- Department of Agricultural Chemistry, Kyoto University, Japan
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10
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Awadé AC, Cleuziat P, Gonzalès T, Robert-Baudouy J. Pyrrolidone carboxyl peptidase (Pcp): an enzyme that removes pyroglutamic acid (pGlu) from pGlu-peptides and pGlu-proteins. Proteins 1994; 20:34-51. [PMID: 7824521 DOI: 10.1002/prot.340200106] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pyrrolidone carboxyl peptidase (EC 3.4.11.8) is an exopeptidase commonly called PYRase, which hydrolytically removes the pGlu-proteins. pGlu also known as pyrrolidone carboxylic acid may occur naturally by an enzymatic procedure or may occur as an artifact in proteins or peptides. The enzymatic synthesis of pGlu suggests that this residue may have important biological and physiological functions. Several studies are consistent with this supposition. PYRase has been found in a variety of bacteria, and in plant, animal, and human tissues. For over two decades, biochemical and enzymatic properties of PYRase have been investigated. At least two classes of PYRase have been characterized. The first one includes the bacterial and animal type I PYRases and the second one the animal type II and serum PYRases. Enzymes from these two classes present differences in their molecular weight and in their enzymatic properties. Recently, the genes of PYRases from four bacteria have been cloned and characterized, allowing the study of the primary structure of these enzymes, and their over-expression in heterelogous organisms. Comparison of the primary structure of these enzymes revealed striking homologies. Type I PYRases and bacterial PYRases are generally soluble enzymes, whereas type II PYRases are membrane-bound enzymes. PYRase II appears to play as important a physiological role as other neuropeptide degrading enzymes. However, the role of type I and bacterial PYRases remains unclear. The primary application of PYRase has been its utilization for some protein or peptide sequencing. Development of chromogenic substrates for this enzyme has allowed its use in bacterial diagnosis.
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Affiliation(s)
- A C Awadé
- Laboratoire de Recherches et de Technologie Laitière, Institut National de la Recherche Agronomique, Rennes, France
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11
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Ramasubbu N, Parthasarathy R. Crystal structure of L-2-oxothiazolidine-4-carboxylic acid. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1989; 34:153-7. [PMID: 2807734 DOI: 10.1111/j.1399-3011.1989.tb01505.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Crystals of the title compound, L-2-oxothiazolidine-4-carboxylic acid, OTC (C4H5NO3S), grown from an aqueous solution are orthorhombic, space group P2(1)2(1)2(1) with the following cell parameters at 22 +/- 3 degrees: a = 5.381(1), b = 5.961(1), c = 17.929(3)A, V = 575.1A(3), Mr = 146.2, Dc = 1.688 g.cm-3, mu = 43.9 cm-1 and Z = 4. The crystal structure was solved by the application of direct methods and refined to an R value of 0.032 for 596 reflections with I greater than 3 sigma(I). The thiazolidine ring adopts a "twist" conformation. This structure contains a short (2.619(3)A) intermolecular hydrogen bond between the carboxyl OH and the oxygen of the 2-oxo moiety, a feature common to most acyl amino acids and acyl peptides.
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Affiliation(s)
- N Ramasubbu
- Center for Crystallographic Research, Roswell Park Memorial Institute, Buffalo, NY
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12
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Seddon AP, Zhao KY, Meister A. Activation of Glutamate by γ-Glutamate Kinase: Formation of γ-cis-Cycloglutamyl Phosphate, an Analog of γ-Glutamyl Phosphate. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)60468-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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13
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14
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Li LY, Seddon AP, Meister A. Interaction of the protein components of 5-oxoprolinase. Substrate-dependent enzyme complex formation. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68670-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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15
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Li LY, Seddon AP, Meister A. 18O studies on the 5-oxoprolinase reaction. Evidence for a phosphorylated tetrahedral intermediate. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)60920-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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16
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Seddon AP, Meister A. Trapping of an intermediate in the reaction catalyzed by 5-oxoprolinase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67276-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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17
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Hershko A, Ciechanover A. The ubiquitin pathway for the degradation of intracellular proteins. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1986; 33:19-56, 301. [PMID: 3025922 DOI: 10.1016/s0079-6603(08)60019-7] [Citation(s) in RCA: 174] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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18
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Abstract
Glutathione functions in catalysis, metabolism, transport, and reductive processes and in protection of cells by destruction of free radicals, reactive oxygen intermediates, and other toxic compounds of endogenous and exogenous origin. It also functions as a storage and transport form of cysteine. Depletion of glutathione (effectively accomplished by inhibition of its synthesis) increases sensitivity to radiation and to certain toxic compounds and is of value in combination with radiation therapy or chemotherapy in situations in which cell selectivity can be achieved. Increased cellular levels of glutathione protect cells against radiation and certain toxic compounds. Glutathione levels can be increased by administration of cysteine or of glutathione, but these approaches are not entirely satisfactory. Cellular glutathione levels can be increased by supplying substrate for gamma-glutamylcysteine synthetase or for glutathione synthetase. L-2-Oxothiazolidine-4-carboxylate is well transported into many cells and is converted by 5-oxoprolinase to cysteine, a substrate of gamma-glutamylcysteine synthetase. gamma-Glutamylcysteine and related compounds are effectively transported, especially into renal cells, thus providing substrate for glutathione synthetase; higher than normal levels of glutathione can be achieved because this enzyme is not significantly inhibited by glutathione, whereas gamma-glutamylcysteine synthetase is feedback-inhibited. Derivatives of glutathione that are effectively transported into cells (glutathione itself is not) offer another means of increasing glutathione levels. The monoethyl ester of glutathione (in which the glycine carboxyl group is esterified) is well transported in vivo into liver and kidney and into cultured fibroblasts and lymphoid cells. Glutathione levels much higher than usual can be obtained by this procedure, which protects lymphoid cells against the lethal effects of irradiation and mice against acetaminophen, and which therefore may be a relatively safe way to increase cellular resistance to radiation and certain toxic compounds.
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19
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20
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Meister A. New aspects of glutathione biochemistry and transport--selective alteration of glutathione metabolism. Nutr Rev 1984; 42:397-410. [PMID: 6151157 DOI: 10.1111/j.1753-4887.1984.tb02277.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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