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Title: Key enzymes of sphingolipid biosynthesis
Author: Yard, Beverley A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2008
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Serine palmitoyl transferase (SPT) catalyses the first and rate limiting step of sphingolipid biosynthesis; a decarboxylative, Claisen condensation of the amino acid L-serine and the long chain fatty acid palmitoyl CoA to produce the first sphingolipid precursor 3-ketodihydrosphingosine. We propose S. paucimobilis as a model organism for the characterisation of sphingolipid biosynthesis. SPT belongs to the α-oxoamine synthase family which are a small group of pyridoxal 5’-phosphate (PLP)-dependent enzymes. This thesis describes spectroscopic studies of recombinant SPT and reports high resolution crystal structures of the PLP, L-serine (substrate) and L-cycloserine (inhibitor) bound forms of S. paucimobilis SPT (1.3, 1.5 and 1.45 Å respectively). These structures are the first of an SPT from any organism and provide an insight into the mechanisms of catalysis and inhibition that take place at the active site of this important enzyme. Another interesting sphingolipid biosynthesis enzyme is Inositol Phosphorylceramide Synthase (IPCS; also known as Aur1p) which is encoded by the AUR1 gene. Deletion or mutation of this gene in S. cerevisiae was found to be lethal therefore highlighting the importance of this enzyme. Aur1p is unique to fungal cells and catalyses the transfer of phosphatidyl inositol onto phytoceramide to produce inositol phosphophytoceramide (IPC). Since it is unique to fungi, Aur1p provides an attractive target for the development of novel anti-fungal agents however it is an integral membrane protein of the Golgi apparatus with 6 predicted transmembrane domains. This means that to date, no structural information is available for Aur1p. Expression of a recombinant, soluble, affinity-tagged Aur1p now paves the way for full characterisation of this important enzyme.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available