Analysis of post-translational modification sites in the aryl hydrocarbon receptor

Keyur Dave (2009). Analysis of post-translational modification sites in the aryl hydrocarbon receptor PhD Thesis, Institute for Molecular Bioscience, The University of Queensland.

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Author Keyur Dave
Thesis Title Analysis of post-translational modification sites in the aryl hydrocarbon receptor
School, Centre or Institute Institute for Molecular Bioscience
Institution The University of Queensland
Publication date 2009-03
Thesis type PhD Thesis
Supervisor Prof. Jeffrey. J. Gorman
Total pages 256
Total colour pages 20
Total black and white pages 236
Subjects 270000 Biological Sciences
Abstract/Summary The dioxin receptor (DR), a transcription factor with basic-helix-loop-helix/PERARNTSIM (bHLH/PAS) homology domains, is activated by toxic xenobiotic ligands leading to severe physiological disturbances most of which are due to deregulation of receptor’s central role in normal development. Activation mechanisms of DR in the presence of exogenous or endogenous ligands are poorly understood. Elucidation of factors involved in the activation of the receptor would assist not only in development of an optimal measure for risk assessment of levels of common environmental pollutants but also in providing novel targets for therapeutic interventions. Posttranslational modifications (PTMs) play an indispensable role in all major signal transduction pathways by increasing the inventory of chemical modifications beyond those already present in the side-chains of common amino acids. Thus, by simple on/off or complex patterns generated by these PTMs, they control a myriad of different biological outcomes. Numerous studies that have suggested an important role of posttranslational modifications in DR activation has prompted a search in this direction, however, apart from phosphorylations at Ser36 and Ser68 no other PTM sites are known. Advanced mass spectrometry (MS)-based characterisation of PTMs is an established technique that can comprehensively provide an accurate cast of all PTM variants and their locations on a protein. This thesis reports the first MS-based comprehensive characterisation of all PTM sites of the purified latent DR and preliminary analysis of identified PTM sites of the activated DR in response to developmental signals (suspension-activated DR) and signals leading to toxic outcomes (ligand-activated DR). The PTM map of the latent DR revealed from this study comprises of 25 phosphorylations, 4 monomethyl-lysines, 2 dimethyl-lysines, 1 O-acetyl-serine and 2 O-sulfono-serines. Most of the phosphorylations and other PTMs were present in the conserved regions of the protein. Investigation of the activated samples of the receptor revealed loss of the above repertoire of modifications and possible presence of some rarer modifications such as O-acetyl-serines in suspension-activated instead of O-sulfonations and pyrophosphorylation at Ser716 in both suspension- as well as ligand-activated DR. A comprehensive mutagenesis study is in progress to understand the functional consequence of each of these modification sites and unravel the functional posttranslational system in DR signalling.
Keyword mass spectrometry, phosphorylation, dioxin receptor, aryl hydrocarbon receptor, proteomics, sulfonation, dimethylation, post-translational modifications
Additional Notes Colour pages in thesis: 4, 11, 15, 26, 31, 43, 85. Also colour pages in chapters with different page numbers as they are published papers: Chapter 4 (paper two) Fig 1S in colour, Chapter 5 (Paper 3) pages 16, 18, 27, 45, 48, 49, supplemental figs pages 11 to 16 all in colour.

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Created: Tue, 11 Aug 2009, 14:36:33 EST by Mr Keyur Dave on behalf of Library - Information Access Service