Members of the 2-oxoglutarate (2OG)- and Fe(II)-dependent oxygenase (2OG oxygenase) superfamily catalyse a wide range of oxidative reactions in biology. 2OG oxygenases require Fe(II) and atmospheric oxygen for their activity, and couple substrate oxidation with the decarboxylation of 2OG into succinate and carbon dioxide. There are more than sixty known 2OG oxygenases in the human genome; they modify small molecules, nucleic acids and proteins implicated in diverse biological processes. Importantly, the seemingly disparate functions of 2OG oxygenases often converge to regulate gene expression. 2OG oxygenases have been shown to affect epigenetic reprogramming, chromatin remodelling, transcription factor activity and mRNA splicing. Emerging evidence indicates that 2OG oxygenases are also involved in the translational control of gene expression. Oxygenases TYW5, ALKBH8, ALKBH5 and FTO were found to catalyse modifications of tRNA and mRNA. The work in this thesis extends these observations by demonstrating that 2OG oxygenase-catalysed protein hydroxylations also play an important role in protein synthesis. The catalytic activities of two oxygenases belonging to the JmjC-only family, NO66 and JMJD4, are described. NO66 catalyses the histidinyl hydroxylation of 60S ribosomal subunit protein L8. NO66 is part of a conserved group of ribosomal protein hydroxylases that can be traced back to prokaryotes. JMJD4 is a lysyl hydroxylase of eRF1, the eukaryotic release factor responsible for translation termination. The hydroxylation of eRF1 takes place on a conserved NIKS motif important for release factor activity, and promotes effcient translational termination. JMJD4 is further implicated in cell growth and cancer, though the link between its activity and tumourigenesis remains to be determined. These results highlight the potential of 2OG oxygenases as regulators of protein synthesis, and further extend the scope of 2OG oxygenase function. The small molecule inhibition of 2OG oxygenases presents a novel therapeutic possibility targeting translational control in cancer and other diseases.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:655026 |
| Date | January 2014 |
| Creators | Feng, Tianshu |
| Contributors | Ratcliffe, Peter; Coleman, Mathew |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:406a311b-dae6-48c6-9785-1e2f0b889e45 |
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