How a single electron (and a proton) modulate binding of the transcription regulator RsrR to DNA
Vendredi 6 septembre 2019 11:00
- Duree : 1 heure
Lieu : Salle des séminaires de l’IBS - 71, avenue des Martyrs - Grenoble
Orateur : Juan FONTECILLA-CAMPS (IBS/Groupe Métalloprotéines)
The recently identified transcriptional regulator RsrR, a member of the dimeric Rrf2 family, has a [2Fe-2S] cluster that is asymmetrically coordinated by two Cys residues from one monomer and His and Glu residues from the other. SvRsrR is known to play a primary role in regulating the relative concentrations of NADH and NAD(P) in the cell. The cluster cycles between +2 and +1 states and this change modulates SvRsrR binding to cognate promoter DNA sequences. In order to understand how a simple one electron redox process can generate the conformational changes necessary to activate or abolish DNA-binding we have detemined high resolution crystal structures of the SvRsrR dimer in different redox states. We find that SvRsrR Trp9 can adopt two conformations, one exposed to the solvent medium and the
other buried in a pre-existing protein cavity, which result in a significant shift in its DNA-binding helix-turn-helix region. Very recent chemical modification solution studies have indicated that these Trp9 conformations are redox-dependent. Furthermore, molecular dynamics simulations have shown that cluster reduction also results in the protonation of His33. Taken together, our studies have allowed us to propose a mechanism of single proton-coupled electron transfer that explains the conformational changes necessary to modulate gene expression through DNA binding.
Contact : ibs.seminaires@ibs.fr
Discipline évènement : (Biologie / Chimie)
Entité organisatrice : (IBS)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire IBS)
Site de l'évènement : Polygone scientifique
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