Porter, Hayley;
(2021)
Identification of diverse cohesin-independent SA interactors that inform SA-specific functions.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Cohesin complexes regulate genome organisation throughout the cell cycle. The molecular mechanisms by which cohesin governs this regulation are still not fully understood. SA1 and SA2 (SA) proteins are critical for cohesin function and are currently considered as core members of the complex due to their ubiquitous interaction with the ring protein members. This thesis investigates the role of the SA proteins in mediating interaction with CTCF. This work determines that following acute depletion of RAD21, SA proteins remain on chromatin and in complex with CTCF. The SA-CTCF interaction is dependent on the presence of nucleic acids and is localised at canonical cohesin binding sites in the genome. Mass spectrometry analysis further determines that cohesin-independent SA1, at least, does not just interact with CTCF, but also a range of additional proteins. The interactome of SA1 in the presence and absence of cohesin is identified. The SA1 interactome includes a wide variety of proteins spanning chromosome organisation, transcription, RNA processing, ribosome biogenesis, and translation. This thesis further reveals that cohesin-independent SA1 is enriched to proteins involved in RNA processing and ribosome biogenesis. R-loop proteins are highly enriched in the SA1 interactome and have previously been identified at sites encompassing all of these processes. Interaction of SA with R-loop structures and RNA itself is confirmed. A functional role for cohesin-independent SA is revealed in the association of cohesin with chromatin in the presence or absence of the NIPBL/MAU2 loader complex. While cohesin is found to load onto chromatin most efficiently in the presence of both SA and NIPBL/MAU2, this work reveals that SA alone can induce cohesin loading in a manner that is specifically linked to the abundance of R-loop structures present in the cell.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Identification of diverse cohesin-independent SA interactors that inform SA-specific functions |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Cancer Institute |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10133985 |
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