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Ouchane S, Steunou AS, Picaud M, Astier C. Aerobic and anaerobic Mg-protoporphyrin monomethyl ester cyclases in purple bacteria: a strategy adopted to bypass the repressive oxygen control system. J Biol Chem 2003; 279:6385-94. [PMID: 14617630 DOI: 10.1074/jbc.m309851200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two different mechanisms for Mg-protoporphyrin monomethyl ester (MgPMe) cyclization are shown to coexist in Rubrivivax gelatinosus and are proposed to be conserved in all facultative aerobic phototrophs: an anaerobic mechanism active under photosynthesis or low oxygenation, and an aerobic mechanism active only under high oxygenation conditions. This was confirmed by analyzing the bacteriochlorophyll accumulation in the wild type and in three mutant strains grown under low or high aeration. A mutant lacking the acsF gene is photosynthetic, exhibits normal bacteriochlorophyll accumulation under low oxygenation and anaerobiosis, and accumulates MgPMe under high oxygenation. The photosynthesis-deficient bchE mutant produces bacteriochlorophyll only under high oxygenation and accumulates MgPMe under low oxygenation and anaerobiosis. The double knockout mutant is devoid of photosystem and accumulates MgPMe under both conditions indicating the involvement of the two enzymes at the same step of the biosynthesis pathway. Oxygen-mediated expression of bchE was studied in the wild type and in a regulatory mutant. The reverse transcriptase-PCR and the bchE promoter activity results demonstrate that the expression of the bchE gene is oxygen-independent and suggest that it is rather the enzyme activity that should be oxygen-sensitive. No obvious sequence similarities were found between oxygen-dependent AcsF and the oxygen-independent anaerobic Mg-protoporphyrin monomethylester cyclase (BchE) enzymes. However, common to all BchE proteins is the conserved CXXX-CXXC sequence. This motif is essential for 4Fe-4S cluster formation in many anaerobic enzymes. Expression and purification of BchE were achieved, and the UV-visible spectral analyses confirmed the presence of an active 4Fe-4S cluster in this protein. The use of different classes of enzymes catalyzing the same reaction under different oxygen growth conditions appears to be a common feature of different biosynthetic pathways, and the benefit of possessing both aerobic and anaerobic systems is discussed.
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Affiliation(s)
- Soufian Ouchane
- Centre de Génétique Moléculaire CNRS (UPR-2167) Bâtiment 26, Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
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52
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Uppsten M, Färnegårdh M, Jordan A, Eliasson R, Eklund H, Uhlin U. Structure of the large subunit of class Ib ribonucleotide reductase from Salmonella typhimurium and its complexes with allosteric effectors. J Mol Biol 2003; 330:87-97. [PMID: 12818204 DOI: 10.1016/s0022-2836(03)00538-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The three-dimensional structure of the large subunit of the first member of a class Ib ribonucleotide reductase, R1E of Salmonella typhimurium, has been determined in its native form and together with three allosteric effectors. The enzyme contains the characteristic ten-stranded alpha/beta-barrel with catalytic residues at a finger loop in its center and with redox-active cysteine residues at two adjacent barrel strands. Structures where the redox-active cysteine residues are in reduced thiol form and in oxidized disulfide form have been determined revealing local structural changes. The R1E enzyme differs from the class Ia enzyme, Escherichia coli R1, by not having an overall allosteric regulation. This is explained from the structure by differences in the N-terminal domain, which is about 50 residues shorter and lacks the overall allosteric binding site. R1E has an allosteric substrate specificity regulation site and the binding site for the nucleotide effectors is located at the dimer interface similarly as for the class Ia enzymes. We have determined the structures of R1E in the absence of effectors and with dTTP, dATP and dCTP bound. The low affinity for ATP at the specificity site is explained by a tyrosine, which hinders nucleotides containing a 2'-OH group to bind.
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Affiliation(s)
- Malin Uppsten
- Department of Molecular Biosciences section of Structure Biology, Uppsala Biomedical Center, Swedish University of Agricultural Sciences, Box 590, Sweden
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53
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Abstract
Disulfide bonds in proteins play various important roles. They are either formed as structural features to stabilize the protein or are found only transiently as part of a catalytic or regulatory cycle. In vivo, the formation and reduction of disulfide bonds is catalyzed by specialized thiol-disulfide exchanging enzymes that contain an active site with the sequence motif Cys-X-X-Cys. These proteins have structurally evolved to catalyze predominantly either oxidative reactions or reductive steps. There is mounting evidence that, in addition to the thiol redox potential, the spatial distribution within different cell compartments and the overall redox state of the cell are equally important. In the cytoplasm, multiple pathways play overlapping roles in the reduction of disulfide bonds and additionally, the expression of several components of thiol-redox pathways was shown to respond to the changes in the cellular thiol-redox equilibrium. In the periplasm, two systems coexist, one catalyzing thiol oxidation and the other disulfide reduction. Recent results suggest that two different mechanisms are used to translocate reducing power from the cytoplasm or to dissipate the electrons after oxidation.
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Affiliation(s)
- D Ritz
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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54
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Masalha M, Borovok I, Schreiber R, Aharonowitz Y, Cohen G. Analysis of transcription of the Staphylococcus aureus aerobic class Ib and anaerobic class III ribonucleotide reductase genes in response to oxygen. J Bacteriol 2001; 183:7260-72. [PMID: 11717286 PMCID: PMC95576 DOI: 10.1128/jb.183.24.7260-7272.2001] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a gram-positive facultative aerobe that can grow in the absence of oxygen by fermentation or by using an alternative electron acceptor. To investigate the mechanism by which S. aureus is able to adapt to changes in oxygen concentration, we analyzed the transcriptional regulation of genes that encode the aerobic class Ib and anaerobic class III ribonucleotide reductase (RNR) systems that are responsible for the synthesis of deoxyribonucleotides needed for DNA synthesis. The S. aureus class Ib RNR nrdIEF and class III RNR nrdDG genes and their regulatory regions were cloned and sequenced. Inactivation of the nrdDG genes showed that the class III RNR is essential for anaerobic growth. Inhibition of aerobic growth by hydroxyurea showed that the class Ib RNR is an oxygen-dependent enzyme. Northern blot analysis and primer extension analysis demonstrated that transcription of class III nrdDG genes is regulated by oxygen concentration and was at least 10-fold higher under anaerobic than under aerobic conditions. In contrast, no significant effect of oxygen concentration was found on the transcription of class Ib nrdIEF genes. Disruption or deletion of S. aureus nrdDG genes caused up to a fivefold increase in nrdDG and nrdIEF transcription under anaerobic conditions but not under aerobic conditions. Similarly, hydroxyurea, an inhibitor of the class I RNRs, resulted in increased transcription of class Ib and class III RNR genes under aerobic conditions. These findings establish that transcription of class Ib and class III RNR genes is upregulated under conditions that cause the depletion of deoxyribonucleotide. Promoter analysis of class Ib and class III RNR operons identified several inverted-repeat elements that may account for the transcriptional response of the nrdIEF and nrdDG genes to oxygen.
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Affiliation(s)
- M Masalha
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
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55
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Stehr M, Schneider G, Aslund F, Holmgren A, Lindqvist Y. Structural basis for the thioredoxin-like activity profile of the glutaredoxin-like NrdH-redoxin from Escherichia coli. J Biol Chem 2001; 276:35836-41. [PMID: 11441020 DOI: 10.1074/jbc.m105094200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NrdH-redoxin is a representative of a class of small redox proteins that contain a conserved CXXC motif and are characterized by a glutaredoxin-like amino acid sequence and thioredoxin-like activity profile. The crystal structure of recombinant Escherichia coli NrdH-redoxin in the oxidized state has been determined at 1.7 A resolution by multiwavelength anomalous diffraction. NrdH-redoxin belongs to the thioredoxin superfamily and is structurally most similar to E. coli glutaredoxin 3 and phage T4 glutaredoxin. The angle between the C-terminal helix alpha3 and strand beta4, which differs between thioredoxin and glutaredoxin, has an intermediate value in NrdH-redoxin. The orientation of this helix is to a large extent determined by an extended hydrogen-bond network involving the highly conserved sequence motif (61)WSGFRP(D/E)(67), which is unique to this subclass of the thioredoxin superfamily. Residues that bind glutathione in glutaredoxins are in general not conserved in NrdH-redoxin, and no glutathione-binding cleft is present. Instead, NrdH-redoxin contains a wide hydrophobic pocket at the surface, similar to thioredoxin. Modeling studies suggest that NrdH-redoxin can interact with E. coli thioredoxin reductase at this pocket and also via a loop that is complementary to a crevice in the reductase in a similar manner as observed in the E. coli thioredoxin-thioredoxin reductase complex.
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Affiliation(s)
- M Stehr
- Division of Molecular Structural Biology and the Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, S-171 77 Sweden
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56
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Monje-Casas F, Jurado J, Prieto-Alamo MJ, Holmgren A, Pueyo C. Expression analysis of the nrdHIEF operon from Escherichia coli. Conditions that trigger the transcript level in vivo. J Biol Chem 2001; 276:18031-7. [PMID: 11278973 DOI: 10.1074/jbc.m011728200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli has two aerobic ribonucleotide reductases encoded by the nrdAB and nrdHIEF operons. While NrdAB is active during aerobiosis, NrdEF is considered a cryptic enzyme with no obvious function. Here, we present evidence that nrdHIEF expression might be important under certain circumstances. Basal transcript levels were dramatically enhanced (25-75-fold), depending on the growth-phase and the growth-medium composition. Likewise, a large increase of >100-fold in nrdHIEF mRNA was observed in bacteria lacking Trx1 and Grx1, the two main NrdAB reductants. Moreover, nrdHIEF expression was triggered in response to oxidative stress, particularly in mutants missing hydroperoxidase I and alkyl-hydroperoxide reductase activities (69.7-fold) and in cells treated with oxidants (up to 23.4-fold over the enhanced transcript level possessed by cells grown on minimal medium). The mechanism(s) that triggers nrdHIEF expression remains unknown, but our findings exclude putative global regulators like RpoS, Fis, cAMP, OxyR, SoxR/S, or RecA. What we have learned about nrdHIEF expression indicates strong differences between its regulation and that of the nrdAB operon and of genes coding for components of both thioredoxin/glutaredoxin pathways. We propose that E. coli might optimize the responses to different stimuli by co-evolving the expression levels for its multiple reductases and electron donors.
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Affiliation(s)
- F Monje-Casas
- Departamento de Bioquimica y Biologia Molecular, Universidad de Córdoba, 14071-Córdoba, Spain
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57
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Sahlin M, Sjöberg BM. Ribonucleotide reductase. A virtual playground for electron transfer reactions. Subcell Biochem 2001; 35:405-43. [PMID: 11192729 DOI: 10.1007/0-306-46828-x_12] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- M Sahlin
- Department of Molecular Biology, Stockholm University, SE-10691 Stockholm, Sweden
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58
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Abstract
We present a summary of recent progress in understanding Escherichia coli K-12 gene and protein functions. New information has come both from classical biological experimentation and from using the analytical tools of functional genomics. The content of the E. coli genome can clearly be seen to contain elements acquired by horizontal transfer. Nevertheless, there is probably a large, stable core of >3500 genes that are shared among all E. coli strains. The gene-enzyme relationship is examined, and, in many cases, it exhibits complexity beyond a simple one-to-one relationship. Also, the E. coli genome can now be seen to contain many multiple enzymes that carry out the same or closely similar reactions. Some are similar in sequence and may share common ancestry; some are not. We discuss the concept of a minimal genome as being variable among organisms and obligatorily linked to their life styles and defined environmental conditions. We also address classification of functions of gene products and avenues of insight into the history of protein evolution.
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Affiliation(s)
- M Riley
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. ,
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59
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Roshick C, Iliffe-Lee ER, McClarty G. Cloning and characterization of ribonucleotide reductase from Chlamydia trachomatis. J Biol Chem 2000; 275:38111-9. [PMID: 10984489 DOI: 10.1074/jbc.m006367200] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In all organisms the deoxyribonucleotide precursors required for DNA synthesis are synthesized from ribonucleotides, a reaction catalyzed by ribonucleotide reductase. In a previous study we showed that Chlamydia trachomatis growth was inhibited by hydroxyurea, an inhibitor of ribonucleotide reductase, and a mutant resistant to the cytotoxic effects of the drug was isolated. Here we report the cloning, expression, and purification of the R1 and R2 subunits of the C. trachomatis ribonucleotide reductase. In comparison with other ribonucleotide reductases, the primary sequence of protein R1 has an extended amino terminus, and the R2 protein has a phenylalanine where the essential tyrosine is normally located. Despite its unusual primary structure, the recombinant enzyme catalyzes the reduction of CDP to dCDP. Results from deletion mutagenesis experiments indicate that while the extended amino terminus of the R1 protein is not required for enzyme activity, it is needed for allosteric inhibition mediated by dATP. Results with site-directed mutants of protein R2 suggest that the essential tyrosine is situated two amino acids downstream of its normal location. Finally, Western blot analysis show that the hydroxyurea-resistant mutant C. trachomatis isolate overexpresses both subunits of ribonucleotide reductase. At the genetic level, compared with wild type C. trachomatis, the resistant isolate has a single base mutation just upstream of the ATG start codon of the R2 protein. The possibility that this mutation affects translational efficiency is discussed.
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Affiliation(s)
- C Roshick
- Department Of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba R3E 0W3, Canada
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60
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Huque Y, Fieschi F, Torrents E, Gibert I, Eliasson R, Reichard P, Sahlin M, Sjoberg BM. The active form of the R2F protein of class Ib ribonucleotide reductase from Corynebacterium ammoniagenes is a diferric protein. J Biol Chem 2000; 275:25365-71. [PMID: 10801858 DOI: 10.1074/jbc.m002751200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Corynebacterium ammoniagenes contains a ribonucleotide reductase (RNR) of the class Ib type. The small subunit (R2F) of the enzyme has been proposed to contain a manganese center instead of the dinuclear iron center, which in other class I RNRs is adjacent to the essential tyrosyl radical. The nrdF gene of C. ammoniagenes, coding for the R2F component, was cloned in an inducible Escherichia coli expression vector and overproduced under three different conditions: in manganese-supplemented medium, in iron-supplemented medium, and in medium without addition of metal ions. A prominent typical tyrosyl radical EPR signal was observed in cells grown in rich medium. Iron-supplemented medium enhanced the amount of tyrosyl radical, whereas cells grown in manganese-supplemented medium had no such radical. In highly purified R2F protein, enzyme activity was found to correlate with tyrosyl radical content, which in turn correlated with iron content. Similar results were obtained for the R2F protein of Salmonella typhimurium class Ib RNR. The UV-visible spectrum of the C. ammoniagenes R2F radical has a sharp 408-nm band. Its EPR signal at g = 2.005 is identical to the signal of S. typhimurium R2F and has a doublet with a splitting of 0.9 millitesla (mT), with additional hyperfine splittings of 0.7 mT. According to X-band EPR at 77-95 K, the inactive manganese form of the C. ammoniagenes R2F has a coupled dinuclear Mn(II) center. Different attempts to chemically oxidize Mn-R2F showed no relation between oxidized manganese and tyrosyl radical formation. Collectively, these results demonstrate that enzymatically active C. ammoniagenes RNR is a generic class Ib enzyme, with a tyrosyl radical and a diferric metal cofactor.
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Affiliation(s)
- Y Huque
- Department of Molecular Biology, Arrhenius Laboratories, Stockholm University, Sweden
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61
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Manganese-dependent ribonucleotide reductase ofPropionibacterium freudenreichii subsp.shermanii: Partial purification, characterization, and role in DNA biosynthesis. Microbiology (Reading) 2000. [DOI: 10.1007/bf02756760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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62
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Jordan A, Torrents E, Sala I, Hellman U, Gibert I, Reichard P. Ribonucleotide reduction in Pseudomonas species: simultaneous presence of active enzymes from different classes. J Bacteriol 1999; 181:3974-80. [PMID: 10383965 PMCID: PMC93887 DOI: 10.1128/jb.181.13.3974-3980.1999] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three separate classes of ribonucleotide reductases exist in nature. They differ widely in protein structure. Class I enzymes are found in aerobic bacteria and eukaryotes; class II enzymes are found in aerobic and anaerobic bacteria; class III enzymes are found in strict and facultative anaerobic bacteria. Usually, but not always, one organism contains only one or two (in facultative anaerobes) classes. Surprisingly, the genomic sequence of Pseudomonas aeruginosa contains sequences for each of the three classes. Here, we show by DNA hybridization that other species of Pseudomonas also contain the genes for three classes. Extracts from P. aeruginosa and P. stutzeri grown aerobically or microaerobically contain active class I and II enzymes, whereas we could not demonstrate class III activity. Unexpectedly, class I activity increased greatly during microaerobic conditions. The enzymes were separated, and the large proteins of the class I enzymes were obtained in close to homogeneous form. The catalytic properties of all enzymes are similar to those of other bacterial reductases. However, the Pseudomonas class I reductases required the continuous presence of oxygen during catalysis, unlike the corresponding Escherichia coli enzyme but similar to the mouse enzyme. In similarity searches, the amino acid sequence of the class I enzyme of P. aeruginosa was more related to that of eukaryotes than to that of E. coli or other proteobacteria, with the large protein showing 42% identity to that of the mouse, suggesting the possibility of a horizontal transfer of the gene. The results raise many questions concerning the physiological function and evolution of the three classes in Pseudomonas species.
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Affiliation(s)
- A Jordan
- Department of Genetics and Microbiology, Faculty of Sciences, Autonomous University of Barcelona, E-08193 Bellaterra, Barcelona, Spain
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63
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64
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Abstract
Ribonucleotide reductases provide the building blocks for DNA replication in all living cells. Three different classes of enzymes use protein free radicals to activate the substrate. Aerobic class I enzymes generate a tyrosyl radical with an iron-oxygen center and dioxygen, class II enzymes employ adenosylcobalamin, and the anaerobic class III enzymes generate a glycyl radical from S-adenosylmethionine and an iron-sulfur cluster. The X-ray structure of the class I Escherichia coli enzyme, including forms that bind substrate and allosteric effectors, confirms previous models of catalytic and allosteric mechanisms. This structure suggests considerable mobility of the protein during catalysis and, together with experiments involving site-directed mutants, suggests a mechanism for radical transfer from one subunit to the other. Despite large differences between the classes, common catalytic and allosteric mechanisms, as well as retention of critical residues in the protein sequence, suggest a similar tertiary structure and a common origin during evolution. One puzzling aspect is that some organisms contain the genes for several different reductases.
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Affiliation(s)
- A Jordan
- Department of Genetics and Microbiology, Faculty of Sciences, Autonomous University of Barcelona, Bellaterra, Spain
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65
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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66
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van Dam PJ, Willems JP, Schmidt PP, Pötsch S, Barra AL, Hagen WR, Hoffman BM, Andersson KK, Gräslund A. High-Frequency EPR and Pulsed Q-Band ENDOR Studies on the Origin of the Hydrogen Bond in Tyrosyl Radicals of Ribonucleotide Reductase R2 Proteins from Mouse and Herpes Simplex Virus Type 1. J Am Chem Soc 1998. [DOI: 10.1021/ja9737127] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pieter J. van Dam
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Jean-Paul Willems
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Peter P. Schmidt
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Stephan Pötsch
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Anne-Laure Barra
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Wilfred R. Hagen
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Brian M. Hoffman
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - K. Kristoffer Andersson
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
| | - Astrid Gräslund
- Contribution from the Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway, Department of Biophysics, Stockholm University, S-106 91 Stockholm, Sweden, and High Magnetic Field Laboratory, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, France
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67
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Affiliation(s)
- JoAnne Stubbe
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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68
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Fieschi F, Torrents E, Toulokhonova L, Jordan A, Hellman U, Barbe J, Gibert I, Karlsson M, Sjöberg BM. The manganese-containing ribonucleotide reductase of Corynebacterium ammoniagenes is a class Ib enzyme. J Biol Chem 1998; 273:4329-37. [PMID: 9468481 DOI: 10.1074/jbc.273.8.4329] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Ribonucleotide reductases (RNRs) are key enzymes in living cells that provide the precursors of DNA synthesis. The three characterized classes of RNRs differ by their metal cofactor and their stable organic radical. We have purified to near homogeneity the enzymatically active Mn-containing RNR of Corynebacterium ammoniagenes, previously claimed to represent a fourth RNR class. N-terminal and internal peptide sequence analyses clearly indicate that the C. ammoniagenes RNR is a class Ib enzyme. In parallel, we have cloned a 10-kilobase pair fragment from C. ammoniagenes genomic DNA, using primers specific for the known class Ib RNR. The cloned class Ib locus contains the nrdHIEF genes typical for class Ib RNR operon. The deduced amino acid sequences of the nrdE and nrdF genes matched the peptides from the active enzyme, demonstrating that C. ammoniagenes RNR is composed of R1E and R2F components typical of class Ib. We also show that the Mn-containing RNR has a specificity for the NrdH-redoxin and a response to allosteric effectors that are typical of class Ib RNRs. Electron paramagnetic resonance and atomic absorption analyses confirm the presence of Mn as a cofactor and show, for the first time, insignificant amounts of iron and cobalt found in the other classes of RNR. Our discovery that C. ammoniagenes RNR is a class Ib enzyme and possesses all the highly conserved amino acid side chains that are known to ligate two ferric ions in other class I RNRs evokes new, challenging questions about the control of the metal site specificity in RNR. The cloning of the entire NrdHIEF locus of C. ammoniagenes will facilitate further studies along these lines.
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Affiliation(s)
- F Fieschi
- Department of Molecular Biology, Stockholm University, S-106 91 Stockholm, Sweden
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69
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Aslund F, Berndt KD, Holmgren A. Redox potentials of glutaredoxins and other thiol-disulfide oxidoreductases of the thioredoxin superfamily determined by direct protein-protein redox equilibria. J Biol Chem 1997; 272:30780-6. [PMID: 9388218 DOI: 10.1074/jbc.272.49.30780] [Citation(s) in RCA: 314] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Glutaredoxins belong to the thioredoxin superfamily of structurally similar thiol-disulfide oxidoreductases catalyzing thiol-disulfide exchange reactions via reversible oxidation of two active-site cysteine residues separated by two amino acids (CX1X2C). Standard state redox potential (E degrees ') values for glutaredoxins are presently unknown, and use of glutathione/glutathione disulfide (GSH/GSSG) redox buffers for determining E degrees ' resulted in variable levels of GSH-mixed disulfides. To overcome this complication, we have used reverse-phase high performance liquid chromatography to separate and quantify the oxidized and reduced forms present in the thiol-disulfide exchange reaction at equilibrium after mixing one oxidized and one reduced protein. This allowed for direct and quantitative pair-wise comparisons of the reducing capacities of the proteins and mutant forms. Equilibrium constants from pair-wise reaction with thioredoxin or its P34H mutant, which have accurately determined E degrees ' values from their redox equilibrium with NADPH catalyzed by thioredoxin reductase, allowed for transformation into standard state values. Using this new procedure, the standard state redox potentials for the Escherichia coli glutaredoxins 1 and 3, which contain identical active site sequences CPYC, were found to be E degrees ' = -233 and -198 mV, respectively. These values were confirmed independently by using the thermodynamic linkage between the stability of the disulfide bond and the stability of the protein to denaturation. Comparison of calculated E degrees ' values from a number of proteins ranging from -270 mV for E. coli Trx to -124 mV for DsbA obtained using this method with those determined using glutathione redox buffers provides independent confirmation of the standard state redox potential of glutathione as -240 mV. Determining redox potentials through direct protein-protein equilibria is of general interest as it overcomes errors in determining redox potentials calculated from large equilibrium constants with the strongly reducing NADPH or by accumulating mixed disulfides with GSH.
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Affiliation(s)
- F Aslund
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, S-171 77 Stockholm, Sweden
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70
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Miranda-Vizuete A, Damdimopoulos AE, Gustafsson J, Spyrou G. Cloning, expression, and characterization of a novel Escherichia coli thioredoxin. J Biol Chem 1997; 272:30841-7. [PMID: 9388228 DOI: 10.1074/jbc.272.49.30841] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Thioredoxin (Trx) is a small ubiquitous protein that displays different functions mainly via redox-mediated processes. We here report the cloning of a gene (trxC) coding for a novel thioredoxin in Escherichia coli as well as the expression and characterization of its product. The gene encodes a protein of 139 amino acids (Trx2) with a calculated molecular mass of 15.5 kDa. Trx2 contains two distinct domains: an N-terminal domain of 32 amino acids including two CXXC motifs and a C-terminal domain, with the conserved active site, Trp-Cys-Gly-Pro-Cys, showing high homology to the prokaryotic thioredoxins. Trx2 together with thioredoxin reductase and NADPH is an efficient electron donor for the essential enzyme ribonucleotide reductase and is also able to reduce the interchain disulfide bridges of insulin. The apparent Km value of Trx2 for thioredoxin reductase is similar to that of the previously characterized E. coli thioredoxin (Trx1). The enzymatic activity of Trx2 as a protein-disulfide reductase is increased by preincubation with dithiothreitol, suggesting that oxidation of cysteine residues other than the ones in the active site might regulate its activity. A truncated form of the protein, lacking the N-terminal domain, is insensitive to the presence of dithiothreitol, further confirming the involvement of the additional cysteine residues in modulating Trx2 activity. In addition, the presence of the N-terminal domain appears to confer heat sensitivity to Trx2, unlike Trx1. Finally, Trx2 is present normally in growing E. coli cells as shown by Western blot analysis.
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Affiliation(s)
- A Miranda-Vizuete
- Department of Biosciences at Novum, Karolinska Institute, S-141 57 Huddinge, Sweden
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71
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Yang F, Curran SC, Li LS, Avarbock D, Graf JD, Chua MM, Lu G, Salem J, Rubin H. Characterization of two genes encoding the Mycobacterium tuberculosis ribonucleotide reductase small subunit. J Bacteriol 1997; 179:6408-15. [PMID: 9335290 PMCID: PMC179557 DOI: 10.1128/jb.179.20.6408-6415.1997] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Two nrdF genes, nrdF1 and nrdF2, encoding the small subunit (R2) of ribonucleotide reductase (RR) from Mycobacterium tuberculosis have 71% identity at the amino acid level and are both highly homologous with Salmonella typhimurium R2F. The calculated molecular masses of R2-1 and R2-2 are 36,588 (322 amino acids [aa]) and 36,957 (324 aa) Da, respectively. Western blot analysis of crude M. tuberculosis extracts indicates that both R2s are expressed in vivo. Recombinant R2-2 is enzymatically active when assayed with pure recombinant M. tuberculosis R1 subunit. Both ATP and dATP are activators for CDP reduction up to 2 and 1 mM, respectively. The gene encoding M. tuberculosis R2-1, nrdF1, is not linked to nrdF2, nor is either gene linked to the gene encoding the large subunit, M. tuberculosis nrdE. The gene encoding MTP64 was found downstream from nrdF1, and the gene encoding alcohol dehydrogenase was found downstream from nrdF2. A nrdA(Ts) strain of E. coli (E101) could be complemented by simultaneous transformation with M. tuberculosis nrdE and nrdF2. An M. tuberculosis nrdF2 variant in which the codon for the catalytically necessary tyrosine was replaced by the phenylalanine codon did not complement E101 when cotransformed with M. tuberculosis nrdE. Similarly, M. tuberculosis nrdF1 and nrdE did not complement E101. Activity of recombinant M. tuberculosis RR was inhibited by incubating the enzyme with a peptide corresponding to the 7 C-terminal amino acid residues of the R2-2 subunit. M. tuberculosis is a species in which a nrdEF system appears to encode the biologically active species of RR and also the only bacterial species identified so far in which class I RR subunits are not arranged on an operon.
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Affiliation(s)
- F Yang
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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72
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Jordan A, Aslund F, Pontis E, Reichard P, Holmgren A. Characterization of Escherichia coli NrdH. A glutaredoxin-like protein with a thioredoxin-like activity profile. J Biol Chem 1997; 272:18044-50. [PMID: 9218434 DOI: 10.1074/jbc.272.29.18044] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ribonucleotides are converted to deoxyribonucleotides by ribonucleotide reductases. Either thioredoxin or glutaredoxin is a required electron donor for class I and II enzymes. Glutaredoxins are reduced by glutathione, thioredoxins by thioredoxin reductase. Recently, a glutaredoxin-like protein, NrdH, was isolated as the functional electron donor for a NrdEF ribonucleotide reductase, a class Ib enzyme, from Lactococcus lactis. The absence of glutathione in this bacterium raised the question of the identity of the intracellular reductant for NrdH. Homologues of NrdH are present in the genomes of Escherichia coli and Salmonella typhimurium, upstream of the genes for the poorly transcribed nrdEF, separated from it by an open reading frame (nrdI) coding for a protein of unknown function. Overexpression of E. coli NrdH protein shows that it is a functional hydrogen donor with higher specificity for the class Ib (NrdEF) than for the class Ia (NrdAB) ribonucleotide reductase. Furthermore, this glutaredoxin-like enzyme is reduced by thioredoxin reductase and not by glutathione. We suggest that several uncharacterized glutaredoxin-like proteins present in the genomes of organisms lacking GSH, including archae, will also react with thioredoxin reductase and be related to the ancestors from which the GSH-dependent glutaredoxins have evolved by the acquisition of a GSH-binding site. We also show that NrdI, encoded by all nrdEF operons, has a stimulatory effect on ribonucleotide reduction.
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Affiliation(s)
- A Jordan
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, S-171 77 Stockholm, Sweden
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73
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Hofer A, Schmidt PP, Gräslund A, Thelander L. Cloning and characterization of the R1 and R2 subunits of ribonucleotide reductase from Trypanosoma brucei. Proc Natl Acad Sci U S A 1997; 94:6959-64. [PMID: 9192674 PMCID: PMC21267 DOI: 10.1073/pnas.94.13.6959] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ribonucleotide reductase (RNR) catalyzes the rate limiting step in the de novo synthesis of deoxyribonucleotides by directly reducing ribonucleotides to the corresponding deoxyribonucleotides. To keep balanced pools of deoxyribonucleotides, all nonviral RNRs studied so far are allosterically regulated. Most eukaryotes contain a class I RNR, which is a heterodimer of two nonidentical subunits called proteins R1 and R2. We have isolated cDNAs encoding the R1 and R2 proteins from Trypanosoma brucei. The amino acid sequence identities with the mouse R1 and R2 subunits are 58% and 63%, respectively. Recombinant active trypanosome R1 and R2 proteins were expressed in Escherichia coli and purified. The R2 protein contains an iron-tyrosyl free radical center verified by EPR spectroscopy and iron analyses. Measurement of cytidine 5'-diphosphate reduction by the trypanosome RNR in the presence of various allosteric effectors showed that the activity is highest with dTTP, dGTP, or dATP and considerably lower with ATP. The effect of dGTP is either activating (alone) or inhibitory (in the presence of ATP). Filter binding studies indicated that there are two classes of allosteric effector binding sites that bind ATP or dATP (low-affinity dATP site) and ATP, dATP, dGTP, or dTTP (high-affinity dATP site), respectively. Therefore, the structural organization of the allosteric sites is very similar to the mammalian RNRs, whereas the allosteric regulation of cytidine 5'-diphosphate reduction is unique. Hopefully, this difference can be used to target the trypanosome RNR for therapeutic purposes.
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Affiliation(s)
- A Hofer
- Department of Medical Biochemistry and Biophysics, Umeâ University, S-901 87 Umeâ, Sweden
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74
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Abstract
A gradient-corrected density functional theory approach (PWP86) has been applied, together with large basis sets (IGLO-III), to investigate the structure and hyperfine properties of model tyrosyl free radicals. In nature, these radicals are observed in, e.g., the charge transfer pathways in photosystem II (PSII) and in ribonucleotide reductases (RNRs). By comparing spin density distributions and proton hyperfine couplings with experimental data, it is confirmed that the tyrosyl radicals present in the proteins are neutral. It is shown that hydrogen bonding to the phenoxyl oxygen atom, when present, causes a reduction in spin density on O and a corresponding increase on C4. Calculated proton hyperfine coupling constants for the beta-protons show that the alpha-carbon is rotated 75-80 degrees out of the plane of the ring in PSII and Salmonella typhimurium RNR, but only 20-30 degrees in, e.g., Escherichia coli, mouse, herpes simplex, and bacteriophage T4-induced RNRs. Furthermore, based on the present calculations, we have revised the empirical parameters used in the experimental determination of the oxygen spin density in the tyrosyl radical in E. coli RNR and of the ring carbon spin densities, from measured hyperfine coupling constants.
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Affiliation(s)
- F Himo
- Department of Physics, Arrhenius Laboratories, Stockholm University, Sweden
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75
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Ribonucleotide reductases — a group of enzymes with different metallosites and a similar reaction mechanism. METAL SITES IN PROTEINS AND MODELS 1997. [DOI: 10.1007/3-540-62870-3_5] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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76
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Eliasson R, Pontis E, Jordan A, Reichard P. Allosteric regulation of the third ribonucleotide reductase (NrdEF enzyme) from enterobacteriaceae. J Biol Chem 1996; 271:26582-7. [PMID: 8900130 DOI: 10.1074/jbc.271.43.26582] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Enterobacteriaceae contain genes for three separate ribonucleotide reductases: nrdAB code for a class Ia enzyme, active during aerobiosis, nrdDG for a class III enzyme, active during anaerobiosis, and nrdEF for a cryptic class Ib enzyme. The NrdEF enzyme provides the active reductase in other, widely different bacteria. Here, we describe the allosteric regulation of the Salmonella typhimurium NrdEF enzyme. It consists of two tightly bound homodimeric proteins, R1E and R2F. Nucleoside triphosphates (ATP, dATP, dGTP, and dTTP) regulate the substrate specificity by binding to a single site of the R1E protein (one nucleotide per polypeptide). Regulation is similar to that of the NrdAB enzyme, with one major exception: dATP stimulates reduction of CDP (and UDP) under conditions when dATP strongly inhibits all activity of the NrdAB enzyme. The nrdA-coded R1 protein contains a second binding site for dATP (and ATP) that controls general enzyme activity. All known R1E proteins lack the 50 N-terminal amino acids of R1, and we propose that the activity site is located in this area of the protein. The more sophisticated regulation of NrdAB enzymes of eukaryotes provides protection against the possibly harmful overproduction of dNTPs.
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Affiliation(s)
- R Eliasson
- Department of Biochemistry 1, Medical Nobel Institute, MBB, Karolinska Institute, 17177 Stockholm, Sweden
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77
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Schmidt PP, Andersson KK, Barra AL, Thelander L, Gräslund A. High field EPR studies of mouse ribonucleotide reductase indicate hydrogen bonding of the tyrosyl radical. J Biol Chem 1996; 271:23615-8. [PMID: 8798575 DOI: 10.1074/jbc.271.39.23615] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Ribonucleotide reductase catalyzes by free radical chemistry the reduction of ribonucleotides to deoxyribonucleotides. The R2 protein of a class 1 ribonucleotide reductase contains a stable tyrosyl radical of neutral phenoxy character, which is necessary for normal enzymatic activity. Here we present the EPR spectra from the tyrosyl free radical in the R2 protein from mouse at 9.62, 115, and 245 GHz. We show that the g-value anisotropy of the mouse R2 radical, when precisely determined from high field EPR spectra, is similar to that of the hydrogen bonded dark stable YD middle dot tyrosyl radical of photosystem II and different from that of the Escherichia coli R2 radical. Because the g-value anisotropy is an important indicator of the hydrogen bonding status of the tyrosyl radical, this result suggests that the mouse R2 radical has its tyrosylate oxygen hydrogen bonded with a D2O exchangeable proton, whereas this hydrogen bond is absent in the E. coli enzyme. It is suggested that the observed proton may be derived from the tyrosine that will become a tyrosyl radical.
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Affiliation(s)
- P P Schmidt
- Department of Biophysics, Arrhenius Laboratories, Stockholm University, S-106 91 Stockholm, Sweden
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78
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Young P, Andersson J, Sahlin M, Sjöberg BM. Bacteriophage T4 anaerobic ribonucleotide reductase contains a stable glycyl radical at position 580. J Biol Chem 1996; 271:20770-5. [PMID: 8702830 DOI: 10.1074/jbc.271.34.20770] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
It has been recently recognized that the class III anaerobic ribonucleotide reductase requires the presence of a second activating gene product, NrdG. We have proposed that the role for NrdG involves the generation of an oxygen sensitive glycyl free radical within the NrdD enzyme. In this article we present the generation of such a glycyl free radical within the T4 NrdD subunit and its dependence upon the phage NrdG subunit. Initially, an overexpression system was created that allowed the joint production of T4 NrdD and T4 NrdG. With this system and in the presence of T4 NrdG, an oxygen-sensitive cleavage of NrdD was observed that mimicked the cleavage observed in phage infected Escherichia coli extracts. Under anaerobic conditions the presence of T4 NrdD with NrdG revealed a strong doublet EPR signal (g = 2.0039). Isotope labeling of the NrdD with [2H]glycine and [13C]glycine, respectively, confirmed the presence of a stabilized glycine radical. The unpaired electron is strongly coupled to C-2 in glycine and the doublet splitting originates from one of the alpha-protons. The glycine residue at position 580 was determined to be the radical containing residue through site-directed mutagenesis studies involving a G580A NrdD mutant. The glycyl radical generation was specific for the T4 NrdG, and the host E. coli NrdG was found to be unable to activate the phage reductase. Finally, anaerobic purification revealed the holoenzyme complex to contain iron, whereas the NrdD polypeptide was found to lack the metal. Our results suggest a tetrameric structure for the T4 anaerobic ribonucleotide reductase containing one homodimer each of NrdD and NrdG, with a single glycyl radical present.
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Affiliation(s)
- P Young
- Department of Molecular Biology, Stockholm University, S-10691 Stockholm, Sweden
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79
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Jordan A, Pontis E, Aslund F, Hellman U, Gibert I, Reichard P. The ribonucleotide reductase system of Lactococcus lactis. Characterization of an NrdEF enzyme and a new electron transport protein. J Biol Chem 1996; 271:8779-85. [PMID: 8621514 DOI: 10.1074/jbc.271.15.8779] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Escherichia coli contains the genetic information for three separate ribonucleotide reductases. Two of them (class I enzymes), coded by the nrdAB and nrdEF genes, respectively, contain a tyrosyl radical, whose generation requires oxygen. The NrdAB enzyme is physiologically active. The function of the nrdEF gene is not known. The third enzyme (class III), coded by nrdDG, operates during anaerobiosis. The DNA of Lactococcus lactis contains sequences homologous to the nrdDG genes. Surprisingly, an nrdD- mutant of L. lactis grew well under standard anaerobic growth conditions. The ribonucleotide reductase system of this mutant was shown to consist of an enzyme of the NrdEF-type and a small electron transport protein. The coding operon contains the nrdEF genes and two open reading frames, one of which (nrdH) codes for the small protein. The same gene organization is present in E. coli. We propose that the aerobic class I ribonucleotide reductases contain two subclasses, one coded by nrdAB, active in E. coli and eukaryotes (class Ia), the other coded by nrdEF, present in various microorganisms (class Ib). The NrdEF enzymes use NrdH proteins as electron transporter in place of thioredoxin or glutaredoxin used by NrdAB enzymes. The two classes also differ in their allosteric regulation by dATP.
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Affiliation(s)
- A Jordan
- Department of Biochemistry 1, Medical Nobel Institute, MBB, Karolinska Institutet, S-17177 Stockholm, Sweden
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80
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Sun X, Ollagnier S, Schmidt PP, Atta M, Mulliez E, Lepape L, Eliasson R, Gräslund A, Fontecave M, Reichard P, Sjöberg BM. The Free Radical of the Anaerobic Ribonucleotide Reductase from Escherichia coli Is at Glycine 681. J Biol Chem 1996. [DOI: 10.1074/jbc.271.12.6827] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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81
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Allard P, Barra AL, Andersson KK, Schmidt PP, Atta M, Gräslund A. Characterization of a New Tyrosyl Free Radical in Salmonella typhimurium Ribonucleotide Reductase with EPR at 9.45 and 245 GHz. J Am Chem Soc 1996. [DOI: 10.1021/ja9529192] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P. Allard
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
| | - A. L. Barra
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
| | - K. K. Andersson
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
| | - P. P. Schmidt
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
| | - M. Atta
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
| | - A. Gräslund
- Department of Biophysics, Arrhenius Laboratories Stockholm University, S-106 91 Stockholm, Sweden High Magnetic Field Laboratory, CNRS B.P. 166, F-38042 Grenoble Cedex, France Department of Biochemistry, University of Oslo P.O. Box 1041, Blindern, N-0316 Oslo, Norway
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82
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Hoganson CW, Sahlin M, Sjöberg BM, Babcock GT. Electron Magnetic Resonance of the Tyrosyl Radical in Ribonucleotide Reductase fromEscherichia coli. J Am Chem Soc 1996. [DOI: 10.1021/ja953979a] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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