Related Experiment Video

Updated: Feb 23, 2026

Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO
13:02

Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO

Published on: December 28, 2019

8.0K

Solution Structure of the N-Terminal Domain of Mediator Subunit MED26 and Molecular Characterization of Its

Zoé Lens1, François-Xavier Cantrelle1, Riccardo Peruzzini1

  • 1UMR8576 Lille University, CNRS, F-59000 Lille, France.

Journal of Molecular Biology
|September 13, 2017
PubMed

Insights

Mediator subunit MED26

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • MED26 is a key subunit of the Mediator complex, regulating RNA Polymerase II transcription.
  • MED26 controls the switch between transcription initiation and elongation.
  • This regulation involves interactions with TAF7 and EAF1.

Purpose of the Study:

  • To elucidate the molecular mechanism by which MED26 regulates transcription initiation and elongation.
  • To determine the structural basis of MED26 N-terminal domain (NTD) interactions with TAF7 and EAF1.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy to solve the structure of MED26-NTD.
  • Peptide binding assays to map interaction sites and determine binding affinities.
  • Site-directed mutagenesis to investigate the role of specific residues in binding.
  • Biophysical techniques (e.g., chemical shift perturbations, NOE) to characterize interactions.

Main Results:

  • The MED26-NTD adopts a 4-helix bundle structure.
  • TAF7 and EAF1 peptides bind to the same groove on MED26-NTD, involving helices H3 and H4.
  • Binding induces a folding-upon-binding mechanism, forming helices in EAF1 and TAF7 peptides.
  • Specific hydrophobic and electrostatic interactions, including residue I222/F223 of TAF7, anchor the TAF7 helix.
  • Mutations in charged residues of TAF7 and EAF1 peptides significantly reduce binding affinity.

Conclusions:

  • MED26-NTD binding to TAF7 and EAF1 is crucial for regulating transcription.
  • The interaction involves a unique folding-upon-binding mechanism and a combination of structural and electrostatic forces.
  • This study provides atomic-level insights into the MED26-mediated transcription switch.
Keywords:
MEDiator complexNMR spectroscopyprotein structureprotein–protein interactiontranscription regulation

More Related Videos

Förster Resonance Energy Transfer Mapping: A New Methodology to Elucidate Global Structural Features07:09

Förster Resonance Energy Transfer Mapping: A New Methodology to Elucidate Global Structural Features

Published on: March 16, 2022

3.1K
Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis09:58

Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis

Published on: June 27, 2020

3.2K

Related Concept Videos

Tail-anchoring of Proteins in the ER Membrane01:45

Tail-anchoring of Proteins in the ER Membrane

Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
3.9K
Structure of Cadherins01:25

Structure of Cadherins

The cadherins were one of the first cell adhesion molecules discovered; the term “cadherins”   is based on their calcium-dependent adhering properties. The first cadherins discovered on the epithelial, neuronal, and placental cells were named E-cadherin, P-cadherin, and N-cadherin, respectively. These classical cadherins share sequence and structural similarities. Other cadherins, including those involved in cell signaling, are grouped into non-classical cadherins. This...
5.0K
Conserved Binding Sites01:49

Conserved Binding Sites

Many proteins’ biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein known as ligand-binding sites. Ligand-binding sites are often conserved among homologous proteins as these sites are critical for protein function.
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally...
5.2K
Assembly of Signaling Complexes01:30

Assembly of Signaling Complexes

Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
6.7K
Generation of Straight or Branched Actin Filaments01:14

Generation of Straight or Branched Actin Filaments

The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
3.9K
Master Transcription Regulators02:23

Master Transcription Regulators

Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a  complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...
7.9K