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89 results on '"Miron, Simona"'

53. Transient Aggregation and Stable Dimerization Induced by Introducing an Alzheimer Sequence into a Water-Soluble Protein

Author

Otzen, Daniel E, Miron, Simona, Akke, Mikael, Oliveberg, Mikael, Otzen, Daniel E, Miron, Simona, Akke, Mikael, and Oliveberg, Mikael

Abstract

Transient contacts between denatured polypeptide chains are likely to play an important part in the initial stages of protein aggregation and fibrillation. To analyze the nature of such contacts, we have carried out a protein engineering study of the 102-residue protein U1A, which aggregates transiently in the wild-type form during refolding from the guanidinium chloride-denatured state. We have prepared a series of mutants with increased aggregation tendencies by increasing the homology between two -strands of U1A and the Alzheimer peptide (-AP). These mutants undergo transient aggregation during refolding, as measured by concentration dependence, double-jump experiments, and binding of ANS, a probe for exposed hydrophobic patches on protein surfaces. The propensity to aggregate increases with increasing homology to -AP. Further, the degree of transient ANS binding correlates reasonably well with the structural parameters recently shown to play a role in the fibrillation of natively unfolded proteins. Two mutants highly prone to transient aggregation, U1A-J and U1A-G, were also studied by NMR. Secondary structural elements of the U1A-J construct (with lower -AP homology) are very similar to those observed in U1A-wt. In contrast, the high-homology construct U1A-G exhibits local unfolding of the C-terminal helix, which packs against the -sheet in the wild-type protein. U1A-G is mainly dimeric according to 15N spin relaxation data, and the dimer interface most likely involves the -sheet. Our data suggest that the transient aggregate relies on specific intermolecular interactions mediated by structurally flexible regions and that contacts may be formed in different -strand registers.

Published
2004
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54. The orientation of the C-terminal domain of the Saccharomyces cerevisiae Rap1 protein is determined by its binding to DNA

Author

Matot, Béatrice, primary, Le Bihan, Yann-Vaï, additional, Lescasse, Rachel, additional, Pérez, Javier, additional, Miron, Simona, additional, David, Gabriel, additional, Castaing, Bertrand, additional, Weber, Patrick, additional, Raynal, Bertrand, additional, Zinn-Justin, Sophie, additional, Gasparini, Sylvaine, additional, and Le Du, Marie-Hélène, additional

Published
2011
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59. Delineation of the Xrcc4-interacting Region in the Globular Head Domain of Cernunnos/XLF

Author

Malivert, Laurent, primary, Ropars, Virginie, additional, Nunez, Marcela, additional, Drevet, Pascal, additional, Miron, Simona, additional, Faure, Guilhem, additional, Guerois, Raphael, additional, Mornon, Jean-Paul, additional, Revy, Patrick, additional, Charbonnier, Jean-Baptiste, additional, Callebaut, Isabelle, additional, and de Villartay, Jean-Pierre, additional

Published
2010
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62. Characterization of a Highly Conserved Binding Site of Mlh1 Required for Exonuclease I-Dependent Mismatch Repair

Author

Dherin, Claudine, primary, Gueneau, Emeric, additional, Francin, Mathilde, additional, Nunez, Marcela, additional, Miron, Simona, additional, Liberti, Sascha Emilie, additional, Rasmussen, Lene Juel, additional, Zinn-Justin, Sophie, additional, Gilquin, Bernard, additional, Charbonnier, Jean-Baptiste, additional, and Boiteux, Serge, additional

Published
2009
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63. Structural and nucleotide-binding properties of YajQ and YnaF, two Escherichia coli proteins of unknown function

Author

Saveanu, Cosmin, primary, Miron, Simona, additional, Borza, Tudor, additional, Craescu, Constantin T., additional, Labesse, Gilles, additional, Gagyi, Cristina, additional, Popescu, Aurel, additional, Schaeffer, Francis, additional, Namane, Abdelkader, additional, Laurent-Winter, Christine, additional, Bârzu, Octavian, additional, and Gilles, Anne-Marie, additional

Published
2008
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65. Structural, Thermodynamic, and Cellular Characterization of Human Centrin 2 Interaction with Xeroderma Pigmentosum Group C Protein

Author

Charbonnier, Jean-Baptiste, primary, Renaud, Emilie, additional, Miron, Simona, additional, Le Du, Marie Hélène, additional, Blouquit, Yves, additional, Duchambon, Patricia, additional, Christova, Petya, additional, Shosheva, Alexandra, additional, Rose, Thierry, additional, Angulo, Jaime F., additional, and Craescu, Constantin T., additional

Published
2007
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81. Structural and nucleotide-binding properties of YajQ and YnaF, two Escherichia coli proteins of unknown function.

Author

Saveanu, Cosmin, Miron, Simona, Borza, Tudor, Craescu, Constantin T., Labesse, Gilles, Gagyi, Cristina, Popescu, Aurel, Schaeffer, Francis, Namane, Abdelkader, Laurent-Winter, Christine, Bârzu, Octavian, and Gilles, Anne-Marie

Abstract

Structural genomics is a new approach in functional assignment of proteins identified via whole-genome sequencing programs. Its rationale is that nonhomologous proteins performing similar or related biological functions might have similar tertiary structure. We used dye pseudoaffinity chromatography, two-dimensional gel electrophoresis, and mass spectrometry to identify two novel Escherichia coli nucleotide-binding proteins, YnaF and YajQ. YnaF exhibited significant sequence identity with MJ0577, an ATP-binding protein from a hyperthermophile ( Methanococcus jannaschii), and with UspA, a protein from Haemophilus influenzae that belongs to the Universal Stress Protein family. YnaF conserves the ATP-binding site and the dimeric structure observed in the crystal of MJ0577. The protein YajQ, present in many bacterial genomes, is missing in eukaryotes. In the absence of significant similarities of YajQ to any solved structure, we determined its structural and ligand-binding properties by NMR and isothermal titration calorimetry. We demonstrate that YajQ is composed of two domains, each centered on a β-sheet, that are connected by two helical segments. NMR studies, corroborated with local sequence conservation among YajQ homologs in various bacteria, indicate that one of the β-sheets is mostly involved in biological activity. [ABSTRACT FROM AUTHOR]

Published
2002
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83. Calbindin D28kExhibits Properties Characteristic of a Ca2+Sensor*

Author

Berggård, Tord, Miron, Simona, Önnerfjord, Patrik, Thulin, Eva, Åkerfeldt, Karin S., Enghild, Jan J., Akke, Mikael, and Linse, Sara

Abstract

Calbindin D28kis a member of the calmodulin superfamily of Ca2+-binding proteins and contains six EF-hands. The protein is generally believed to function as a Ca2+buffer, but the studies presented in this work indicate that it may also act as a Ca2+sensor. The results show that Mg2+binds to the same sites as Ca2+with an association constant of ∼1.4·103m−1in 0.15 mKCl. The four high affinity sites in calbindin D28kbind Ca2+in a non-sequential, parallel manner. In the presence of physiological concentrations of Mg2+, the Ca2+affinity is reduced by a factor of 2, and the cooperativity, which otherwise is modest, increases. Based on the binding constants determined in the presence of physiological salt concentrations, we estimate that at the Ca2+concentration in a resting cell calbindin D28kis saturated to 40–75% with Mg2+but to less than 9% with Ca2+. In contrast, the protein is expected to be nearly fully saturated with Ca2+at the Ca2+level of an activated cell. A substantial conformational change is observed upon Ca2+binding, but only minor structural changes take place upon Mg2+binding. This suggests that calbindin D28kundergoes Ca2+-induced structural changes upon Ca2+activation of a cell. Thus, calbindin D28kdisplays several properties that would be expected for a protein involved in Ca2+-induced signal transmission and hence may function not only as a Ca2+buffer but also as a Ca2+sensor. Digestion patterns resulting from limited proteolysis of the protein suggest that the loop of EF-hand 2, a variant site that does not bind Ca2+, becomes exposed upon Ca2+binding.

Published
2002
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84. A new subfamily of short bacterial adenylate kinases with the Mycobacteriumtuberculosisenzyme as a model: A predictive and experimental study

Author

Munier‐Lehmann, Hélène, Burlacu‐Miron, Simona, Craescu, Constantin T., Mantsch, Henry H., and Schultz, Christian P.

Abstract

The adkgene from Mycobacterium tuberculosiscodes for an enzyme of 181 amino acids. A sequence comparison with 52 different forms of adenylate kinases (AK) suggests that the enzyme from M. tuberculosisbelongs to a new subfamily of “short” bacterial AKs. The recombinant protein, overexpressed in Escherichia coli, exhibits a low catalytic activity and an unexpectedly high thermal stability (Tm = 64.8°C). Based on various spectroscopic data, on the known three‐dimensional structure of the AK from E. coliand on secondary structure predictions for various sequenced AKs, we propose a structural model for AK from M. tuberculosis(AKmt). Proteins 1999;36:238–248. © 1999 Wiley‐Liss, Inc.

Published
1999
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85. Crystallization and preliminary X-ray diffraction data of the complex between human centrin 2 and a peptide from the protein XPC.

Author

Shosheva, Alexandra, Stura, Enrico, Charbonnier, Jean-Baptiste, Christova, Petya, Le Du, Marie Hélène, Miron, Simona, Blouquit, Yves, Duchambon, Patricia, and Craescu, Constantin T.

Subjects
X-ray diffraction, CRYSTALLIZATION, PEPTIDES, POLYETHYLENE glycol, HYDROGEN-ion concentration, CALORIMETRY
Abstract

Centrins are highly conserved calcium-binding proteins involved in the nucleotide-excision repair pathway as a subunit of the heterotrimer including the XPC and hHR23B proteins. A complex formed by a Ca2+-bound human centrin 2 construct (the wild type lacking the first 25 amino acids) with a 17-mer peptide derived from the XPC sequence (residues Asn847-Arg863) was crystallized. Data were collected to 1.65 A resolution from crystals grown in 30% monomethyl polyethylene glycol (MPEG) 500, 100 mM NaCl and 100 mM Bicine pH 9.0. Crystals are monoclinic and belong to space group C2, with two molecules in the asymmetric unit. The unit-cell parameters are a = 60.28, b = 59.42, c = 105.14 Å, a = y = 90, β = 94.67°. A heavy-atom derivative was obtained by co-crystallization with Sr2+. The substitution was rationalized by calorimetry experiments, which indicate a binding constant for Sr2+ of 4.0 × 104 M-1. [ABSTRACT FROM AUTHOR]

Published
2006
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86. Di-phosphorylated BAF shows altered structural dynamics and binding to DNA, but interacts with its nuclear envelope partners

Author

Marcelot, Agathe, Petitalot, Ambre, Ropars, Virginie, Le Du, Marie-Hélène, Samson, Camille, Dubois, Stevens, Hoffmann, Guillaume, Miron, Simona, Cuniasse, Philippe, Marquez, Jose Antonio, Thai, Robert, Theillet, François-Xavier, and Zinn-Justin, Sophie

Subjects
3. Good health
Abstract

Nucleic acids research / Special publication 49(7), 3841 - 3855 (2021). doi:10.1093/nar/gkab184, Barrier-to-autointegration factor (BAF), encoded by the BANF1 gene, is an abundant and ubiquitously expressed metazoan protein that has multiple functions during the cell cycle. Through its ability to cross-bridge two double-stranded DNA (dsDNA), it favours chromosome compaction, participates in post-mitotic nuclear envelope reassembly and is essential for the repair of large nuclear ruptures. BAF forms a ternary complex with the nuclear envelope proteins lamin A/C and emerin, and its interaction with lamin A/C is defective in patients with recessive accelerated aging syndromes. Phosphorylation of BAF by the vaccinia-related kinase 1 (VRK1) is a key regulator of BAF localization and function. Here, we demonstrate that VRK1 successively phosphorylates BAF on Ser4 and Thr3. The crystal structures of BAF before and after phosphorylation are extremely similar. However, in solution, the extensive flexibility of the N-terminal helix α1 and loop α1α2 in BAF is strongly reduced in di-phosphorylated BAF, due to interactions between the phosphorylated residues and the positively charged C-terminal helix α6. These regions are involved in DNA and lamin A/C binding. Consistently, phosphorylation causes a 5000-fold loss of affinity for dsDNA. However, it does not impair binding to lamin A/C Igfold domain and emerin nucleoplasmic region, which leaves open the question of the regulation of these interactions., Published by Information Retrieval Ltd., London

87. Molecular interactions between Wells-Dawson type polyoxometalates and human serum albumin.

Author

Zhang G, Keita B, Craescu CT, Miron S, de Oliveira P, and Nadjo L

Subjects
Calorimetry, Circular Dichroism, Fluorescence, Hot Temperature, Humans, Molecular Structure, Copper chemistry, Nickel chemistry, Phosphorus Compounds chemistry, Serum Albumin chemistry, Tungsten Compounds chemistry
Abstract

Binding human serum albumin (HSA) of three polyoxometalates (POMs) with the Wells-Dawson structure, alpha(2)-[P2W17O61]10- (abbreviated as alpha(2)-P2W17) and two of its metal-substituted derivatives, alpha(2)-[NiP2W17O61]8- and alpha(2)-[CuP2W17O61]8- (alpha(2)-P2W17Ni and alpha(2)-P2W17Cu, respectively) was studied in an aqueous medium at pH 7.5. Fluorescence quenching, circular dichroism (CD), thermal denaturation, and isothermal titration calorimetry (ITC) were used for this purpose. The results were compared with those obtained previously with the Keggin structure POM, [H2W12O40]6- (H2W12), and the wheel-shaped structure, [NaP5W30O110]14- (P5W30). All these POMs bind HSA mainly by electrostatic interactions. Comparison of the physical characteristics and HSA interaction parameters for the POMs of the present work and those studied previously showed that the overall charge of the clusters is not the single parameter governing the binding process and its consequences. In contrast, besides the influences of the structure, the dimension and/or weight of the POMs, the results have permitted highlighting of the importance of each POM atomic composition for its binding behavior.

Published
2008
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88. The N-terminal domain of human centrin 2 has a closed structure, binds calcium with a very low affinity, and plays a role in the protein self-assembly.

Author

Yang A, Miron S, Duchambon P, Assairi L, Blouquit Y, and Craescu CT

Subjects
Amino Acid Sequence, Binding Sites, Calorimetry, Humans, Models, Molecular, Molecular Sequence Data, Protein Conformation, Protein Folding, Protein Structure, Secondary, Sequence Homology, Amino Acid, Structure-Activity Relationship, Substrate Specificity, Thermodynamics, Calcium metabolism, Calcium-Binding Proteins chemistry, Calcium-Binding Proteins metabolism, Cell Cycle Proteins chemistry, Cell Cycle Proteins metabolism
Abstract

Centrins are well-conserved calcium binding proteins from the EF-hand superfamily implicated in various cellular functions, such as centrosome duplication, DNA repair, and nuclear mRNA export. The intrinsic molecular flexibility and the self-association tendency make difficult the structural characterization of the integral protein. In this paper we report the solution structure, the Ca2+ binding properties, and the intermolecular interactions of the N-terminal domain of two human centrin isoforms, HsCen1 and HsCen2. In the absence of Ca2+, the N-terminal construct of HsCen2 revealed a compact core conformation including four almost antiparallel alpha-helices and a short antiparallel beta-sheet, very similar to the apo state structure of other calcium regulatory EF-hand domains. The first 25 residues show a highly irregular and dynamic structure. The three-dimensional model for the N-terminal domain of HsCen1, based on the high sequence conservation and NMR spectroscopic data, shows very close structural properties. Ca2+ titration of the apo-N-terminal domain of HsCen1 and HsCen2, monitored by NMR spectroscopy, revealed a very weak affinity (10(2)-10(3) M(-1)), suggesting that the cellular role of this domain is not calcium dependent. Isothermal calorimetric titrations showed that an 18-residue peptide, derived from the N-terminal unstructured fragment, has a significant affinity (approximately 10(5) M(-1)) for the isolated C-terminal domain, suggesting an active role in the self-assembly of centrin molecules.

Published
2006
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89. Structural and nucleotide-binding properties of YajQ and YnaF, two Escherichia coli proteins of unknown function.

Author

Saveanu C, Miron S, Borza T, Craescu CT, Labesse G, Gagyi C, Popescu A, Schaeffer F, Namane A, Laurent-Winter C, Bârzu O, and Gilles AM

Subjects
Adenosine Triphosphate metabolism, Amino Acid Sequence, Calorimetry, Circular Dichroism, Dimerization, Escherichia coli Proteins genetics, Escherichia coli Proteins isolation & purification, Ligands, Models, Molecular, Molecular Sequence Data, Molecular Structure, Nuclear Magnetic Resonance, Biomolecular, Nucleotides metabolism, Protein Binding, Protein Conformation, Protein Structure, Secondary, Protein Structure, Tertiary, Proteome, RNA-Binding Proteins genetics, RNA-Binding Proteins isolation & purification, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins metabolism, Sequence Alignment, Escherichia coli Proteins chemistry, Escherichia coli Proteins metabolism, RNA-Binding Proteins chemistry, RNA-Binding Proteins metabolism
Abstract

Structural genomics is a new approach in functional assignment of proteins identified via whole-genome sequencing programs. Its rationale is that nonhomologous proteins performing similar or related biological functions might have similar tertiary structure. We used dye pseudoaffinity chromatography, two-dimensional gel electrophoresis, and mass spectrometry to identify two novel Escherichia coli nucleotide-binding proteins, YnaF and YajQ. YnaF exhibited significant sequence identity with MJ0577, an ATP-binding protein from a hyperthermophile (Methanococcus jannaschii), and with UspA, a protein from Haemophilus influenzae that belongs to the Universal Stress Protein family. YnaF conserves the ATP-binding site and the dimeric structure observed in the crystal of MJ0577. The protein YajQ, present in many bacterial genomes, is missing in eukaryotes. In the absence of significant similarities of YajQ to any solved structure, we determined its structural and ligand-binding properties by NMR and isothermal titration calorimetry. We demonstrate that YajQ is composed of two domains, each centered on a beta-sheet, that are connected by two helical segments. NMR studies, corroborated with local sequence conservation among YajQ homologs in various bacteria, indicate that one of the beta-sheets is mostly involved in biological activity.

Published
2002
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