Regulation of Pyrimidine Base and Ribonucleotide Metabolism in Pseudomonas Oleovorans

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Date of Award

Fall 2020

Abstract

Regulation of the pyrimidine base and ribonucleotide metabolism was studied in Pseudomonas oleovorans ATCC 8062. The pyrimidine salvage pathway enzyme activities in ATCC 8062 were assayed in cells grown under different culture conditions. Catabolite repression of the pyrimidine salvage pathway enzyme activities in P. oleovorans by selected carbon sources was studied. It was observed that the carbon sources succinate, glucose and glycerol showed catabolite repression to a higher degree than fructose on the pyrimidine nucleotide N-ribosidase and cytosine deaminase activities. When a succinate minimal medium containing pyrimidine bases or ribonucleosides as possible nitrogen sources was used, it was seen that pyrimidine nucleotide N-ribosidase activity was affected little unless it was grown on dihydrouracil as a nitrogen source. In contrast, cytosine deaminase activity was significantly affected by growth on cytosine as well as the dihydropyrimidine bases dihydrouracil and dihydrothymine as nitrogen sources. The largest increase in cytosine deaminase activity was observed following the growth of ATCC 8062 cells on dihydrouracil as a nitrogen source which was identical to the effect observed for pyrimidine nucleotide N-ribosidase activity. Overall, the findings indicated that the pyrimidine base reductive pathway catabolite dihydrouracil plays an important role in activating the pyrimidine salvage pathway enzymes pyrimidine nucleotide N-ribosidase and cytosine deaminase activities to provide pyrimidine bases for catabolism in P. oleovorans ATCC 8062 while catabolite repression of these enzymes appears less consequential.

Advisor

Thomas West

Subject Categories

Chemistry | Physical Sciences and Mathematics

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