The Control of The Pyrimidine Biosynthesis Pathways in Pseudomonas Aureofaciens
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
Date of Award
1-10-2024
Abstract
The control of the pyrimidine biosynthetic pathway by pyrimidines was investigated in the biological control agent Pseudomonas aureofaciens ATCC 17418. The de novo pyrimidine biosynthetic enzymes displayed higher activity in the P. aureofaciens glucose-grown cells compared to succinate-grown cells. In the pyrimidine (uracil or orotic acid) supplementation experiment, orotic acid had more effect on aspartate transcarbamoylase, dihydroorotase and dihydroorotate dehydrogenase when P. aureofaciens cells were grown on glucose. Two pyrimidine auxotrophic mutants from P. aureofaciens were isolated via conventional mutagenesis and resistance to 5-fluoroorotic acid in order to ascertain whether pyrimidine limitation triggers pathway enzyme overproduction due to repressor scarcity. Strain GW-1 was orotate phosphoribosyltransferase deficient while the second mutant strain GW-2 was defective for orotidine 5’- monophosphate decarboxylase. The pyrimidine limitation experiment of both mutants showed an important derepression of some pyrimidine biosynthetic enzyme activities, especially aspartate transcarbamoylase, dihydroorotase. The regulation of the first enzyme of the de novo pyrimidine biosynthetic pathway was examined. In P. aureofaciens, aspartate transcarbamoylase was inhibited by PPi, ATP, UTP and ADP. It was observed that pyrimidine formation was controlled by at the transcriptional level and at the level of aspartate transcarbamoylase activity.
Advisor
Thomas West
Subject Categories
Chemistry | Physical Sciences and Mathematics
Recommended Citation
Gore, Lou Vamina, "The Control of The Pyrimidine Biosynthesis Pathways in Pseudomonas Aureofaciens" (2024). Electronic Theses & Dissertations. 1149.
https://digitalcommons.tamuc.edu/etd/1149
