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H2020Individual fellowship2015–2017

SFSASP · Structural and Functional Studies of ATRX- Syndrome Protein

Horizon 2020 — Marie Skłodowska-Curie Actions

Duration
2015-09-01 → 2017-08-31
EU contribution
€195,455
Participants
1
Scheme
MSCA-IF-EF-ST

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Results in brief

Structural and Functional Studies of ATRX- Syndrome Protein

The project aimed at understanding the molecular basis of function of ATRX, a protein that when mutated causes ATRX syndrome. Using structure-function approaches, our investigations addressed different aspects of ATRX function in cells. ATRX syndrome is characterized by severe mental retardation, thalassemia, facial deformities and disability. ATRX is a serious genetic disorder, which results in a considerable increase in both acute and chronic morbidity, and mortality. Although ATRX is a rare disease, treatment is intensive and the lifetime cost of treating an ATRX patient is estimated to be ~£800,000. There is potential for commercialisation and exploitation of the scientific knowledge originated from this research as understanding how ATRX interacts with its target sequences may provide new druggable targets. Moreover, ATRX has also been implicated in many cancers, particularly in sarcomas, and the knowledge gained from our work will also improve the tools available to diagnose and treat cancers that display ATRX deregulation. The overall aim of the project was to define at a molecular level how ATRX remodels chromatin. Objective 1: To elucidate the structure of ATRX Snf2 domain by X-ray crystallography at various steps in ATP hydrolysis cycle Objective 2: To investigate the structural preference of ATRX for various DNA substrates that are likely to be formed at interstitial repeat regions where ATRX is known to bind in vivo. Objective 3: To investigate the interaction of ATRX with DAXX and Histone 3.3 Our main result from this project was the dissection of the ATRX - MeCP2 interaction in the context of the ATRX/RETT syndrome mutations. We were able to show direct interaction between ATRX and MeCP2. We have observed that this interaction is abrogated by most of the RETT-causing mutations in MeCP2. We are at present investigating if ATRX syndrome-causing mutations in ATRX also affect this interaction.

Data: CORDIS, © European Union

Project objective

The eukaryotic genome is packaged into chromatin, which needs to be unpacked to provide necessary access by cellular factors for varied cellular functions. However, DNA can be rendered accessible by the action of energy-consuming chromatin remodelling proteins. One such protein is ATRX that harbours an N-terminal plant homeodomain (PHD) and a C-terminal helicase domain that confers ATPase activity and identifies ATRX as a member of the snf2 family member of chromatin remodellers. ATRX has been shown to localize in vivo with constitutive heterochromatin in pericentromeric regions as well as telomeres where it works in complex with DAXX for the deposition of the Histone3.3. Mutations in the ATRX gene give rise to ATR-X syndrome, a severe X-linked mental retardation syndrome often accompanied by alpha-thalassemia. Mounting evidence links ATRX mutations to cancer and to malignancies that depend on a telomerase-independent pathway of telomere maintenance called the ‘alternative lengthening of telomeres (ALT) pathway, linking ATRX to aging. Despite these advances however, there is lack of understanding of the molecular mechanism of ATRX and of its role within these pathologies. The proposed research aims to investigate the structural and functional properties of ATRX, and to define at a molecular level how it interacts with DAXX to remodel chromatin. We will use a combination of biophysical techniques like NMR, Isothermal Calorimetry and western blotting to characterize ATRX interaction with partner proteins. X-ray crystallography, Cryo-electron microscopy and Small angle X-ray scattering techniques will be used to elucidate the structure of ATRX complexes. We will also design assays to measure the enzymatic activity of the ATRX snf2 domain by itself and in presence of DNA and/or its interacting partners. These studies will provide insight into a potential new mechanism of chromatin remodelling and will help us elucidate the consequences of disease-related ATRX mutations.

Original text from CORDIS.

Participants

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Data: CORDIS, © European Union