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The human respiratory syncytial virus M 2-1 transcription antiterminator is an essential elongation factor required by the RNA polymerase for effective transcription beyond the first two nonstructural genes. Its exclusive presence in pneumovirus among all paramyxovirus suggests a unique function within this small genus. With the aim of understanding its biochemical properties, we investigated this α-helical tetramer by making use of a biophysical approach. We found that the tetramer hydrodynamic radius is considerably extended at high ionic strengths and determined its zinc content to be one atom per monomer. Dissociation-unfolding experiments show a fully reversible and concentration-dependent cooperative transition, but secondary and tertiary structural changes are uncoupled at lower protein concentrations. We detect the presence of a monomeric intermediate, which can be classified as a "late molten globule" with substantial secondary and tertiary structure. Global fittings of experiments from three different probes at two M 2-1 concentrations provide a free energy of dissociation-unfolding of -36.8 ± 0.1 kcal mol -1, corresponding to a tight dissociation constant of 10 -28 M 3 at pH 7.0. The tetramer affinity is strongly governed by pH, with a free energy change of 13 kcal mol -1 when pH decreases from 7.0 to 5.0 (K D = 10 -18 M 3). The drastic changes that take place within a pH range compatible with a cellular environment strongly suggest a regulatory effect of pH on M 2-1 structure and biochemical properties, likely affecting transcription and interaction with proteins and RNA. © 2011 American Chemical Society.


Documento: Artículo
Título:The respiratory syncytial virus transcription antiterminator M 2-1 is a highly stable, zinc binding tetramer with strong pH-dependent dissociation and a monomeric unfolding intermediate
Autor:Esperante, S.A.; Chemes, L.B.; Sánchez, I.E.; De Prat-Gay, G.
Filiación:Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBA-Conicet, Patricias Argentinas 435, 1405 Buenos Aires, Argentina
Protein Physiology Laboratory, Departamento de Quimì Ica Bioloìgica, Univ. de Buenos Aires and Consejo Nac. de Investigaciones Cientifi Icas y Teci Nicas de Argentina, C1428EGA Buenos Aires, Argentina
Palabras clave:Biochemical properties; Cellular environment; Concentration-dependent; Cooperative transitions; Dissociation constant; Elongation factor; Free energy change; Global fitting; High ionic strength; Hydrodynamic Radius; Molten globule; Monomeric intermediate; pH range; PH-dependent; Protein concentrations; Regulatory effects; Respiratory syncytial virus; RNA polymerase; Secondary and tertiary structures; Structural change; Tetramers; Zinc binding; Zinc content; Dissociation; Experiments; Free energy; Genes; Ionic strength; Oligomers; pH effects; RNA; Viruses; Zinc; Transcription; monomer; protein M2; protein M2-1; RNA; RNA polymerase; tetramer; unclassified drug; virus protein; zinc; alpha helix; article; atom; biochemistry; circular dichroism; fluorescence spectroscopy; hydrodynamics; ionic strength; light scattering; nonhuman; pH; Pneumovirinae; priority journal; protein determination; protein tertiary structure; protein unfolding; regulator gene; Respiratory syncytial pneumovirus; Humans; Hydrogen-Ion Concentration; Kinetics; Peptide Elongation Factors; Protein Binding; Protein Folding; Protein Multimerization; Protein Stability; Protein Unfolding; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human; Viral Proteins; Zinc; Human respiratory syncytial virus; Paramyxoviridae; Pneumovirus; Respiratory syncytial virus
Página de inicio:8529
Página de fin:8539
Título revista:Biochemistry
Título revista abreviado:Biochemistry
CAS:RNA, 63231-63-0; RNA polymerase, 9014-24-8; zinc, 14378-32-6, 7440-66-6; Peptide Elongation Factors; Viral Proteins; Zinc, 7440-66-6


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---------- APA ----------
Esperante, S.A., Chemes, L.B., Sánchez, I.E. & De Prat-Gay, G. (2011) . The respiratory syncytial virus transcription antiterminator M 2-1 is a highly stable, zinc binding tetramer with strong pH-dependent dissociation and a monomeric unfolding intermediate. Biochemistry, 50(40), 8529-8539.
---------- CHICAGO ----------
Esperante, S.A., Chemes, L.B., Sánchez, I.E., De Prat-Gay, G. "The respiratory syncytial virus transcription antiterminator M 2-1 is a highly stable, zinc binding tetramer with strong pH-dependent dissociation and a monomeric unfolding intermediate" . Biochemistry 50, no. 40 (2011) : 8529-8539.
---------- MLA ----------
Esperante, S.A., Chemes, L.B., Sánchez, I.E., De Prat-Gay, G. "The respiratory syncytial virus transcription antiterminator M 2-1 is a highly stable, zinc binding tetramer with strong pH-dependent dissociation and a monomeric unfolding intermediate" . Biochemistry, vol. 50, no. 40, 2011, pp. 8529-8539.
---------- VANCOUVER ----------
Esperante, S.A., Chemes, L.B., Sánchez, I.E., De Prat-Gay, G. The respiratory syncytial virus transcription antiterminator M 2-1 is a highly stable, zinc binding tetramer with strong pH-dependent dissociation and a monomeric unfolding intermediate. Biochemistry. 2011;50(40):8529-8539.