Search

Your search keyword '"Gräslund, Astrid"' showing total 34 results
Start Over Author "Gräslund, Astrid" Journal journal of biological chemistry
34 results on '"Gräslund, Astrid"'

12. Translocation of Dynorphin Neuropeptides across the Plasma Membrane

Author

Marinova, Zoya, primary, Vukojević, Vladana, additional, Surcheva, Slavina, additional, Yakovleva, Tatiana, additional, Cebers, Gvido, additional, Pasikova, Natalia, additional, Usynin, Ivan, additional, Hugonin, Loïc, additional, Fang, Weijie, additional, Hallberg, Mathias, additional, Hirschberg, Daniel, additional, Bergman, Tomas, additional, Langel, Ülo, additional, Hauser, Kurt F., additional, Pramanik, Aladdin, additional, Aldrich, Jane V., additional, Gräslund, Astrid, additional, Terenius, Lars, additional, and Bakalkin, Georgy, additional

Published
2005
Full Text
View/download PDF

28. Mammalian p53R2 Protein Forms an Active Ribonucleotide Reductasein Vitrowith the R1 Protein, Which Is Expressed Both in Resting Cells in Response to DNA Damage and in Proliferating Cells*

Author

Guittet, Olivier, Håkansson, Pelle, Voevodskaya, Nina, Fridd, Susan, Gräslund, Astrid, Arakawa, Hirofumi, Nakamura, Yusuke, and Thelander, Lars

Abstract

Recently, a homologue of the small subunit of mammalian ribonucleotide reductase (RNR) was discovered, called p53R2. Unlike the well characterized S phase-specific RNR R2 protein, the new form was induced in response to DNA damage by the p53 protein. Because the R2 protein is specifically degraded in late mitosis and absent in Go/G1cells, the induction of the p53R2 protein may explain how resting cells can obtain deoxyribonucleotides for DNA repair. However, no direct demonstration of RNR activity of the p53R2 protein was presented and furthermore, no corresponding RNR large subunit was identified. In this study we show that recombinant, highly purified human and mouse p53R2 proteins contain an iron-tyrosyl free radical center, and both proteins form an active RNR complex with the human and mouse R1 proteins. UV irradiation of serum-starved, Go/G1-enriched mouse fibroblasts, stably transformed with an R1 promoter-luciferase reporter gene construct, caused a 3-fold increase in luciferase activity 24 h after irradiation, paralleled by an increase in the levels of R1 protein. Taken together, our data indicate that the R1 protein can function as the normal partner of the p53R2 protein and that an R1-p53R2 complex can supply resting cells with deoxyribonucleotides for DNA repair.

Published
2001
Full Text
View/download PDF

29. Electron Paramagnetic Resonance Evidence for a Novel Interconversion of [3Fe-4S]+and [4Fe-4S]+Clusters with Endogenous Iron and Sulfide in Anaerobic Ribonucleotide Reductase Activase in Vitro*210

Author

Liu, Aimin and Gräslund, Astrid

Abstract

We report an EPR study of the iron-sulfur enzyme, anaerobic ribonucleotide reductase activase from Lactococcus lactis. The activase (nrdGgene) together withS-adenosyl-l-methionine (AdoMet) give rise to a glycyl radical in the NrdD component. A semi-reduced [4Fe-4S]+cluster with an axially symmetric EPR signal was produced upon photochemical reduction of the activase. Air exposure of the reduced enzyme gave a [3Fe-4S]+cluster. The Fe3S4cluster was convertible to the EPR-active [4Fe-4S]+cluster by renewed treatment with reducing agents, demonstrating a reversible [3Fe-4S]+- to-[4Fe-4S]+cluster conversion without exogenous addition of iron or sulfide. Anaerobic reduction of the activase by a moderate concentration of dithionite also resulted in a semi-reduced [4Fe-4S]+cluster. Prolonged reduction gave an EPR-silent fully reduced state, which was enzymatically inactive. Both reduced states gave the [3Fe-4S]+EPR signal after air exposure. The iron-sulfur cluster interconversion was also studied in the presence of AdoMet. The EPR signal of semi-reduced activase-AdoMet had rhombic symmetry and was independent of which reductant was applied, whereas the EPR signal of the [3Fe-4S]+cluster after air exposure was unchanged. The results indicate that an AdoMet-mediated [4Fe-4S]+center is the native active species that induces the formation of a glycyl radical in the NrdD component.

Published
2000
Full Text
View/download PDF

30. Evidence by Mutagenesis that Tyr370of the Mouse Ribonucleotide Reductase R2 Protein Is the Connecting Link in the Intersubunit Radical Transfer Pathway*

Author

Rova, Ulrika, Adrait, Annie, Pötsch, Stephan, Gräslund, Astrid, and Thelander, Lars

Abstract

Ribonucleotide reductase catalyzes all de novosynthesis of deoxyribonucleotides. The mammalian enzyme consists of two non-identical subunits, the R1 and R2 proteins, each inactive alone. The R1 subunit contains the active site, whereas the R2 protein harbors a binuclear iron center and a tyrosyl free radical essential for catalysis. It has been proposed that the radical properties of the R2 subunit are transferred ∼35 Å to the active site of the R1 protein, through a coupled electron/proton transfer along a conserved hydrogen-bonded chain, i.e.a radical transfer pathway (RTP). To gain a better insight into the properties and requirements of the proposed RTP, we have used site-directed mutagenesis to replace the conserved tyrosine 370 in the mouse R2 protein with tryptophan or phenylalanine. This residue is located close to the flexible C terminus, known to be essential for binding to the R1 protein. Our results strongly indicate that Tyr370links the RTP between the R1 and R2 proteins. Interruption of the hydrogen-bonded chain in Y370F inactivates the enzyme complex. Alteration of the same chain in Y370W slows down the RTP, resulting in a 58 times lower specific activity compared with the native R2 protein and a loss of the free radical during catalysis.

Published
1999
Full Text
View/download PDF

31. Cross-interactions between the Alzheimer Disease Amyloid-β Peptide and Other Amyloid Proteins: A Further Aspect of the Amyloid Cascade Hypothesis.

Author

Jinghui Luo, Wärmländer, Sebastian K. T. S., Gräslund, Astrid, and Abrahams, Jan Pieter

Subjects
*ALZHEIMER'S disease, *AMYLOID beta-protein, *PROTEIN folding, *AMINO acid sequence, *DISEASE progression
Abstract

Many protein folding diseases are intimately associated with accumulation of amyloid aggregates. The amyloid materials formed by different proteins/peptides share many struxctural similarities, despite sometimes large amino acid sequence differences. Some amyloid diseases constitute risk factors for others, and the progression of one amyloid disease may affect the progression of another. These connections are arguably related to amyloid aggregates of one protein being able to directly nucleate amyloid formation of another, different protein: the amyloid cross-interaction. Here, we discuss such cross-interactions between the Alzheimer′s disease amyloid-β(Aβ) peptide and other amyloid proteins in the context of what is known from in vitro and in vivo experiments, and of what might be learned from clinical studies. The aim is to clarify potential molecular associations between different amyloid diseases. We argue that the amyloid cascade hypothesis in Alzheimer′s disease should be expanded to include cross-interactions between Aβ and other amyloid proteins. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

32. Non-chaperone Proteins Can Inhibit Aggregation and Cytotoxicity of Alzheimer Amyloid β Peptide.

Author

Jinghui Luo, Wärmländer, Sebastian K. T. S., Gräslund, Astrid, and Abrahams, Jan Pieter

Subjects
*AMYLOID beta-protein, *PEPTIDES, *MOLECULAR chaperones, *ALZHEIMER'S disease treatment, *ALBUMINS
Abstract

Many factors are known to influence the oligomerization, fibrillation, and amyloid formation of the Aβ peptide that is associated with Alzheimer disease. Other proteins that are present when Aβ peptides deposit in vivo are likely to have an effect on these aggregation processes. To separate specific versus broad spectrum effects of proteins on Aβ aggregation, we tested a series of proteins not reported to have chaperone activity: catalase, pyruvate kinase, albumin, lysozyme, α-lactalbumin, and β-lactoglobulin. All tested proteins suppressed the fibrillation of Alzheimer Aβ(1-40) peptide at substoichiometric ratios, albeit some more effectively than others. All proteins bound non-specifically to Aβ, stabilized its random coils, and reduced its cytotoxicity. Surprisingly, pyruvate kinase and catalase were at least as effective as known chaperones in inhibiting Aβ aggregation. We propose general mechanisms for the broad-spectrum inhibition Aβ fibrillation by proteins. The mechanisms we discuss are significant for prognostics and perhaps even for prevention and treatment of Alzheimer disease. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

33. The Involvement of Arg265 of Mouse Ribonucleotide Reductase R2 Protein in Proton Transfer and Catalysis.

Author

Narváez, Ana J., Voevodskaya, Nina, Thelander, Lars, and Gräslund, Astrid

Subjects
*DEOXYRIBONUCLEOTIDES, *PARTICLES (Nuclear physics), *GENETIC mutation, *ORGANIC acids, *TRANSCRIPTION factors, *GENE expression, *GENETIC regulation, *BIOCHEMISTRY
Abstract

Ribonucleotide reductase class I enzymes consist of two nonidentical subunits, R1 and R2, the latter containing a diiron carboxylate center and a stable tyrosyl radical (Tyr•), both essential for catalysis. Catalysis is known to involve highly conserved amino acid residues covering a range of ∼35 Å and a concerted mechanism involving long range electron transfer, probably coupled to proton transfer. A number of residues involved in electron transfer in both the R1 and R2 proteins have been identified, but no direct model has been presented regarding the proton transfer side of the process. Arg265 is conserved in all known sequences of class Ia R2. In this study we have used site-directed mutagenesis to gain insight into the role of this residue, which lies close to the catalytically essential Asp266 and Trp103. Mutants to Arg265 included replacement by Ala, Glu, Gin, and Tyr. All mutants of Arg265 were found to have no or low catalytic activity with the exception of Arg265 to Glu, which shows ∼40% of the activity of native R2. We also found that the Arg mutants were capable of stable tyrosyl radical generation, with similar kinetics of radical formation and R1 binding as native R2. Our results, supported by molecular modeling, strongly suggest that Arg265 is involved in the proton-coupled electron transfer pathway and may act as a proton mediator during catalysis. [ABSTRACT FROM AUTHOR]

Published
2006
Full Text
View/download PDF

34. A New Tyrosyl Radical on Phe208 as Ligand to the Diiron Center in Escherichia coli Ribonucleotide Reductase, Mutant R2-Y122H.

Author

Kolberg, Matthias, Logan, Derek T., Bleifuss, Gunther, Pötsch, Stephan, Sjöberg, Britt-Marie, Gräslund, Astrid, Lubitz, Wolfgang, Lassmann, Günter, and Lendzian, Friedhelm

Subjects
*TYROSINE, *PHENYLALANINE, *ESCHERICHIA coli, *NUCLEOPROTEINS, *AMINO acids, *BIOCHEMISTRY
Abstract

The R2 protein subunit of class I ribonucleotide reductase (RNR) belongs to a structurally related family of oxygen bridged diiron proteins. In wild-type R2 of Escherichia coli, reductive cleavage of molecular oxygen by the diferrous iron center generates a radical on a nearby tyrosine residue (Tyr122), which is essential for the enzymatic activity of RNR, converting ribonucleotides into deoxyribonucleotides. In this work, we characterize the mutant E. coli protein R2-Y122H, where the radical site is substituted with a histidine residue. The x-ray structure verifies the mutation. R2-Y122H contains a novel stable paramagnetic center which we name H, and which we have previously proposed to be a diferric iron center with a strongly coupled radical, FeIIIFeIIIR. Here we report a detailed characterization of center H, using ¹H/²H- 14N/15N- and 57Fe-ENDOR in comparison with the FeIIIFeIV intermediate X observed in the iron reconstitution reaction of R2. Specific deuterium labeling of phenylalanine residues reveals that the radical results from a phenylalanine. As Phe208 is the only phenylalanine in the ligand sphere of the iron site, and generation of a phenyl radical requires a very high oxidation potential, we propose that in Y122H residue Phe208 is hydroxylated, as observed earlier in another mutant (R2-Y122F/E238A), and further oxidized to a phenoxyl radical, which is coordinated to Fe1. This work demonstrates that small structural changes can redirect the reactivity of the diiron site, leading to oxygenation of a hydrocarbon, as observed in the structurally similar methane monoxygenase, and beyond, to formation of a stable iron-coordinated radical. [ABSTRACT FROM AUTHOR]

Published
2005
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results