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Structural characterisation of the SMRT co-repressor complex and the Aster-A protein

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posted on 2020-07-10, 09:20 authored by Jennifer E. Gurnett
Histone deacetylases (HDACs) are involved in removing acetyl groups from lysine residues on histone tails resulting in gene repression. The SMRT/NCoR complex is a class I HDAC co-repressor complex the core of which includes the proteins HDAC3, TBL1/TBLR1 and GPS2. The SMRT/NCoR complex is targeted to chromatin by unliganded nuclear receptors and can also be seen as a drug target. Structures have already been published of the TBL1 N-terminal domain, the GPS2/SMRT coiled coil and HDAC3/SMRT but the structure of the core SMRT complex is not known. A model based on the current known structures has been derived from negative stain and cryo-EM to create a 3D model of the core SMRT complex. Complementary techniques such as crosslinking-mass spectrometry and SAXS have been used to support and complement the EM models converging on a consensus model for the core SMRT complex. The crystal structure of the HDAC3:SMRT complex identified an inositol phosphate positioned at the interface between HDAC3 and SMRT. This as fuelled future work which has shown that inositol phosphates are able to activate the HDAC containing complexes. HDAC activity assays and fluorescence polarisation experiments have been performed with a range of inositol phosphate derivatives to probe the binding pocket to assess the potential as a therapeutic target. The Aster-A protein is also regulated by nuclear receptors, LXR in particular. The structure of this protein bound to 25-hydroxycholesterol ligand has been determined by X-ray crystallography which has revealed details of its mechanism of action. A flexible W1 loop may be required for entry and exit of the cholesterol into the partially open ligand-binding cavity.

History

Supervisor(s)

John Schwabe; Shaun Cowley

Date of award

2020-03-06

Author affiliation

Department of Molecular and Cell Biology

Awarding institution

University of Leicester

Qualification level

  • Doctoral

Qualification name

  • PhD

Language

en

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