Regulation and substrate specificity of the USP1-UAF1 deubiquitinase complex

Arkinson, Connor (2020) Regulation and substrate specificity of the USP1-UAF1 deubiquitinase complex. PhD thesis, University of Glasgow.

Abstract

Ubiquitination regulates numerous cellular signalling pathways in eukaryotes, such as DNA replication, cell cycle control and protein turnover. Ubiquitination is a reversible post-translational modification involving the assembly and removal of ubiquitin proteins. A superfamily of proteases known as the deubiquitinases (DUBs) target ubiquitin and remove it from substrates. As well as modifying thousands of target protein sites, ubiquitin is also conjugated to other ubiquitins at various sites, forming ubiquitin chains. This results in an enormous range of structurally diverse ubiquitin signals that a relatively small array of DUBs are required to regulate. The USP1 DUB, along with its activating binding partner UAF1, regulates a structurally diverse array of site-specifically monoubiquitinated substrates including PCNA-K164Ub, FANCD2-K561Ub and FANCI-K523Ub. Loss of USP1-UAF1 activity results in genomic instability, but how USP1 targets its substrates or is regulated by UAF1 is poorly understood. For example, how does a deubiquitinase (e.g. USP1) display high promiscuity yet target specific substrates? In this thesis, the minimal requirements for deubiquitination of FANCD2-K561Ub, FANCI-K523Ub and PCNA-K164Ub (USP1 physiological substrates) are determined by reconstitution and dissection of USP1. This thesis presents new insights into how DUBs achieve specific deubiquitination of ubiquitin-substrate conjugates and provides a molecular rationale for USP1 as the DUB for FANCD2-Ub.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: DNA repair, ubiquitin, deubiquitinases, USP1, UAF1, FANCD2, PCNA, FANCI, ICL, Fanconi Anemia.
• Subjects: Q Science > QR Microbiology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences > Molecular Biosciences
• Supervisor's Name: Walden, Professor Helen
• Date of Award: 2020
• Embargo Date: 14 December 2023
• Depositing User: Mr Connor Arkinson
• Unique ID: glathesis:2020-76772
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 17 Dec 2019 17:09
• Last Modified: 14 May 2024 15:40
• Thesis DOI: 10.5525/gla.thesis.76772
• URI: https://theses.gla.ac.uk/id/eprint/76772