title: Fragment-Based NMR Study of the Conformational Dynamics in the bHLH Transcription Factor Ascl1.
abstract: The Achaete-scute homolog 1 (Ascl1) protein regulates a large subset of genes that leads neuronal progenitor cells to distinctive differentiation pathways during human brain development. Although it is well known that Ascl1 binds DNA as a homo- or heterodimer via its basic helix-loop-helix (bHLH) motif, little is known about the conformational sampling properties of the DNA-free full-length protein, and in particular about the bHLH domain-flanking N- and C-terminal segments, which are predicted to be highly disordered in solution. The structural heterogeneity, low solubility, and high aggregation propensity of Ascl1 in aqueous buffer solutions make high-resolution studies of this protein a challenging task. Here, we have adopted a fragment-based strategy that allowed us to obtain high-quality NMR data providing, to our knowledge, the first comprehensive high-resolution information on the structural propensities and conformational dynamics of Ascl1. The emerging picture is that of an overall extended and highly dynamic polypeptide chain comprising three helical segments and lacking persistent long-range interactions. We also show that the C-terminal helix of the bHLH domain is involved in intermolecular interactions, even in the absence of DNA. Our results contribute to a better understanding of the mechanisms of action that govern the regulation of proneural transcription factors.
authors.affiliation: BioTalentum Ltd., Gödöllő, Hungary.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Baronti
authors.affiliation: Institut de Biologie Structurale, Université Grenoble, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Grenoble, France; Centre National de la Recherche Scientifique (CNRS), Grenoble, France.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Hošek
authors.affiliation: Institut de Biologie Structurale, Université Grenoble, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Grenoble, France; Centre National de la Recherche Scientifique (CNRS), Grenoble, France.
authors.forename: Sergio
authors.initials: S
authors.lastname: Gil-Caballero
authors.affiliation: BioTalentum Ltd., Gödöllő, Hungary.
authors.forename: Hadas
authors.initials: H
authors.lastname: Raveh-Amit
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Sesto Fiorentino, Italy.
authors.forename: Eduardo O
authors.initials: EO
authors.lastname: Calçada
authors.affiliation: Institut de Biologie Structurale, Université Grenoble, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Grenoble, France; Centre National de la Recherche Scientifique (CNRS), Grenoble, France.
authors.forename: Isabel
authors.initials: I
authors.lastname: Ayala
authors.affiliation: BioTalentum Ltd., Gödöllő, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Dinnyés
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Sesto Fiorentino, Italy; Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino, Italy. Electronic address: felli@cerm.unifi.it.
authors.forename: Isabella C
authors.initials: IC
authors.lastname: Felli
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Sesto Fiorentino, Italy; Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino, Italy. Electronic address: pierattelli@cerm.unifi.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Pierattelli
authors.affiliation: Institut de Biologie Structurale, Université Grenoble, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Grenoble, France; Centre National de la Recherche Scientifique (CNRS), Grenoble, France. Electronic address: bernhard.brutscher@ibs.fr.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brutscher
mesh_terms: D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D000072417:Protein Domains
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; C065500:ASCL1 protein, human