Let There be Morphine: Structural Insights into Functional and Evolutionary Relationships of Morphine Biosynthesis in Opium Poppy

Carr, Samuel Clyde

Let There be Morphine: Structural Insights into Functional and Evolutionary Relationships of Morphine Biosynthesis in Opium Poppy

dc.contributor.advisor	Facchini, Peter
dc.contributor.advisor	Ng, Kenneth
dc.contributor.author	Carr, Samuel Clyde
dc.contributor.committeemember	Ro, Dae-Kyun
dc.contributor.committeemember	Moorhead, Gregory
dc.contributor.committeemember	Noskov, Sergei
dc.date	2024-06
dc.date.accessioned	2023-12-01T18:52:23Z
dc.date.available	2023-12-01T18:52:23Z
dc.date.issued	2023-11-30
dc.description.abstract	Benzylisoquinoline alkaloids are a large and diverse class of plant specialized metabolites known for their pharmaceutical properties, including the tumor suppressant noscapine, vasodilator papaverine, antimicrobial sanguinarine, and the important analgesics codeine, morphine, and their semisynthetic derivatives. The latter group of analgesics are known as morphinan alkaloids or opiates and are produced solely in select members of the genus Papaver, most importantly Papaver somniferum commonly known as opium poppy. This thesis highlights the use of structural biology in multidisciplinary approaches to understand the biosynthesis of morphinan alkaloids in opium poppy and related species. Dehydroreticuline reductase and codeinone reductase are closely related enzymes from the aldo-keto reductase superfamily catalyzing the second and second-last steps, respectively, in morphine biosynthesis in opium poppy. The elucidation of the crystal structure of codeinone reductase reveals novel structural features allowing for the in-depth analysis of substrate binding and catalysis leading to the engineering of substrate specificity. This structure also provides the means for the homology modeling of dehydroreticuline reductase giving insight into its novel catalytic mechanism. Transcriptomic analysis of representative Papaver species reveals putative morphinan biosynthetic enzyme orthologues and the ubiquitous distribution of dehydroreticuline reductase and codeinone reductase, among other morphinan biosynthetic enzymes. Structural analysis and functional/kinetic characterization of aldo-keto reductases demonstrates the ubiquitous conservation of dehydroreticuline reductase and codeinone reductase activity in the genus Papaver. These results challenge the current evolutionary narrative of morphinan biosynthesis suggesting: [1] a more ancient neofunctionalization of early enzymatic steps of morphinan biosynthesis than previously believed and [2] that morphinan biosynthesis evolved via the patchwork evolutionary model. Enzymatic latency and ligand binding affinity both provide a platform for the neofunctionalization of novel enzymatic activities. The alkaloid binding capabilities of pathogenesis related 10 proteins provides a means to understand the neofunctionalization of the morphine biosynthetic enzymes thebaine synthase and neopinone isomerase, alongside a biological role in alkaloid storage for abundant non-catalytic pathogenesis related 10 proteins. Their binding to alkaloids is predicted to promote the formation of protein-alkaloid aggregates based on binding-induced conformational changes observed through X-ray crystallography and dramatic changes in sucrose gradient fractionation.
dc.identifier.citation	Carr, S. C. (2023). Let there be morphine: structural insights into functional and evolutionary relationships of morphine biosynthesis in opium poppy (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/117608
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Opium Poppy
dc.subject	Opiates
dc.subject	Morphine
dc.subject	Plant Specialized Metabolism
dc.subject	Biology
dc.subject	Biochemistry
dc.subject	Structural Biology
dc.subject	Evolution
dc.subject	Benzylisoquinoline Alkaloids
dc.subject.classification	Biochemistry
dc.subject.classification	Botany
dc.title	Let There be Morphine: Structural Insights into Functional and Evolutionary Relationships of Morphine Biosynthesis in Opium Poppy
dc.type	doctoral thesis
thesis.degree.discipline	Biological Sciences
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I require a thesis withhold – I need to delay the release of my thesis due to a patent application, and other reasons outlined in the link above. I have/will need to submit a thesis withhold application.