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The flexibility of a homeodomain transcription factor heterodimer and its allosteric regulation by DNA binding
Author(s) -
Mathiasen Lisa,
Valentini Erica,
Boivin Stephane,
Cattaneo Angela,
Blasi Francesco,
Svergun Dmitri I.,
Bruckmann Chiara
Publication year - 2016
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13801
Subject(s) - allosteric regulation , isothermal titration calorimetry , dna , small angle x ray scattering , biophysics , dimer , circular dichroism , transcription factor , chemistry , protein–dna interaction , biology , biochemistry , microbiology and biotechnology , dna binding protein , gene , scattering , physics , organic chemistry , optics , enzyme
Transcription factors are known to modify the DNA that they bind. However, DNA can also serve as an allosteric ligand whose binding modifies the conformation of transcriptional regulators. Here, we describe how heterodimer PBX 1: PREP 1, formed by proteins playing major roles in embryonic development and tumorigenesis, undergoes an allosteric transition upon DNA binding. We demonstrate through a number of biochemical and biophysical methods that PBX 1: PREP 1 exhibits a structural change upon DNA binding. Small‐angle X‐ray scattering ( SAXS ), circular dichroism ( CD ), isothermal titration calorimetry ( ITC ), and limited proteolysis demonstrate a different shape, α‐helical content, thermodynamic behavior, and solution environment of the holo‐complex (with DNA ) compared to the apo‐complex (without DNA ). Given that PBX 1 as such does not have a defined DNA selectivity, structural changes upon DNA binding become major factors in the function of the PBX 1: PREP 1 complex. The observed changes are mapped at both the amino‐ and carboxy‐terminal regions of the two proteins thereby providing important insights to determine how PBX 1: PREP 1 dimer functions. Database Small‐angle scattering data are available in SASBDB under accession numbers SASDAP7, SASDAQ7, and SASDAR7.