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  • 1.
    Andersson, Jessica
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Bodevin, Sabrina
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Westman, Mariann
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sahlin, Margareta
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sjöberg, Britt-Marie
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Two Active Site Asparagines Are Essential for the Reaction Mechanism of the Class III Anaerobic Ribonucleotide Reductase from Bacteriophage T42001In: The Journal of Biological Chemistry, Vol. 44, p. 40457-40463Article in journal (Refereed)
  • 2.
    Bendegard, Saga
    et al.
    Stockholm University, Faculty of Humanities, Department of Swedish Language and Multilingualism, Institute for Interpreting and Translation Studies.
    Melander Marttala, UllaWestman, MariaStockholm University, Faculty of Humanities, Department of Swedish Language and Multilingualism, Scandinavian Languages.
    Språk och norm: Rapport från ASLA:s symposium, Uppsala universitet 21−22 april 20162017Conference proceedings (editor) (Refereed)
  • 3.
    Kasrayan, Alex
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Larsson-Birgander, Pernilla
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Pappalardo, Lucia
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Regnström, Karin
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Westman, MariAnn
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Slaby, Agneta
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Gordon, Euan
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sjöberg, Britt-Marie
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Enhancement by effectors and substrate nucleotides of R1-R2 interactions in Escherichia coli class Ia ribonucleotide reductase.2004In: J Biol Chem, ISSN 0021-9258, Vol. 279, no 30, p. 31050-7Article in journal (Other academic)
    Abstract [en]

    Ribonucleotide reductases are a family of essential enzymes that catalyze the reduction of ribonucleotides to their corresponding deoxyribonucleotides and provide cells with precursors for DNA synthesis. The different classes of ribonucleotide reductase are distinguished based on quaternary structures and enzyme activation mechanisms, but the components harboring the active site region in each class are evolutionarily related. With a few exceptions, ribonucleotide reductases are allosterically regulated by nucleoside triphosphates (ATP and dNTPs). We have used the surface plasmon resonance technique to study how allosteric effects govern the strength of quaternary interactions in the class Ia ribonucleotide reductase from Escherichia coli, which like all class I enzymes has a tetrameric alpha(2) beta(2) structure. The component alpha(2)called R1 harbors the active site and two types of binding sites for allosteric effector nucleotides, whereas the beta(2) component called R2 harbors the tyrosyl radical necessary for catalysis. Our results show that only the known allosteric effector nucleotides, but not non-interacting nucleotides, promote a specific interaction between R1 and R2. Interestingly, the presence of substrate together with allosteric effector nucleotide strengthens the complex 2-3 times with a similar free energy change as the mutual allosteric effects of substrate and effector nucleotide binding to protein R1 in solution experiments. The dual allosteric effects of dATP as positive allosteric effector at low concentrations and as negative allosteric effector at high concentrations coincided with an almost 100-fold stronger R1-R2 interaction. Based on the experimental setup, we propose that the inhibition of enzyme activity in the E. coli class Ia enzyme occurs in a tight 1:1 complex of R1 and R2. Most intriguingly, we also discovered that thioredoxin, one of the physiological reductants of ribonucleotide reductases, enhances the R1-R2 interaction 4-fold.

  • 4.
    Torrents, Eduard
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Westman, MariAnn
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sahlin, Margareta
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sjöberg, Britt-Marie
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Ribonucleotide reductase modularity: Atypical duplication of the ATP-cone domain in Pseudomonas aeruginosa.2006In: J Biol Chem, ISSN 0021-9258, Vol. 281, no 35, p. 25287-96Article in journal (Other academic)
    Abstract [en]

    The opportunistic pathogen Pseudomonas aeruginosa, which causes serious nosocomial infections, is a gamma-proteobacterium that can live in many different environments. Interestingly P. aeruginosa encodes three ribonucleotide reductases (RNRs) that all differ from other well known RNRs. The RNR enzymes are central for de novo synthesis of deoxyribonucleotides and essential to all living cells. The RNR of this study (class Ia) is a complex of the NrdA protein harboring the active site and the allosteric sites and the NrdB protein harboring a tyrosyl radical necessary to initiate catalysis. P. aeruginosa NrdA contains an atypical duplication of the N-terminal ATP-cone, an allosteric domain that can bind either ATP or dATP and regulates the overall enzyme activity. Here we characterized the wild type NrdA and two truncated NrdA variants with precise N-terminal deletions. The N-terminal ATP-cone (ATP-c1) is allosterically functional, whereas the internal ATP-cone lacks allosteric activity. The P. aeruginosa NrdB is also atypical with an unusually short lived tyrosyl radical, which is efficiently regenerated in presence of oxygen as the iron ions remain tightly bound to the protein. The P. aeruginosa wild type NrdA and NrdB proteins form an extraordinarily tight complex with a suggested alpha4beta4 composition. An alpha2beta2 composition is suggested for the complex of truncated NrdA (lacking ATP-c1) and wild type NrdB. Duplication or triplication of the ATP-cone is found in some other bacterial class Ia RNRs. We suggest that protein modularity built on the common catalytic core of all RNRs plays an important role in class diversification within the RNR family.

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