Degree Name
MS (Master of Science)
Program
Biology
Date of Award
12-2025
Committee Chair or Co-Chairs
Tianhu Sun
Committee Members
Dhirendra Kumar, Anoop Arunagiri
Abstract
Carotenoids are vital for plant growth and human health, functioning as light-harvesting pigments and structural components of photosystems. β-carotene and α-carotene are precursors of vitamin A, essential for vision and immunity, and its deficiency causes blindness in developing countries. Metabolic engineering targets carotenoid biosynthesis, particularly phytoene synthase (PSY), a key rate-limiting enzyme. Tomato PSY1 is dominant in fruits but less efficient than PSY2, making PSY2 an attractive target with conserved sequences across plants. In this study, a semi-rational, structure-guided mutagenesis of the tomato PSY2 gene enables screening of high-activity mutants in a bacterial system that can accumulate carotenoids, with plans to implement automation using the Opentron Flex pipetting robot platform, which can process 96 samples simultaneously in a single run. In the long term, machine learning could model protein sequence-enzyme activity relationships to guide future rounds of directed evolution. Ultimately, identified key residues could be used as targets for prime editing to boost provitamin A production in crops.
Document Type
Thesis - embargo
Recommended Citation
Nossir, Fayrouz, "Directed Evolution to Enhance Phytoene Synthase Enzyme Activity for Metabolic Engineering" (2025). Electronic Theses and Dissertations. Paper 4632. https://dc.etsu.edu/etd/4632
Copyright
Copyright by the authors.
