Regulation of Microbial Nucleic Acid Metabolism

Abstract

The basic area of my research program has focused on examining the regulation of nucleic acid metabolism from an evolutionary perspective. My laboratory has been investigating the control of pyrimidine biosynthesis in pseudomonads relative to their evolving taxonomy. Pyrimidine biosynthesis is essential to prokaryotic and eukaryotic cells as it provides the substrates (UTP, CTP, dCTP and dTTP) necessary for the synthesis of RNA and DNA. There are six de novo pyrimidine biosynthetic enzymes in this pathway as can be seen below. The enzyme aspartate transcarbamoylase is the first one solely unique to this biosynthetic pathway. It has undergone much scrutiny at the level of enzyme activity since it is regulated by feedback inhibition by pyrimidine nucleotides in numerous species. My laboratory has shown that the regulation of this enzyme does differ according to the DNA homology group to which the species has been assigned. Moreover, my laboratory has demonstrated that the regulation of pyrimidine biosynthetic enzyme synthesis in species of Pseudomonas is regulated by pyrimidines which changed the view that pyrimidine biosynthesis was not regulated in pseudomonads. My laboratory has also investigated the regulation of the enzyme aspartate transcarbamoylase in pseudomonads. The regulation of aspartate transcarbamoylase in pseudomonads is different than what has been observed for the Escherichia coli enzyme. It is the goal of this REU project to allow a student to learn how to process cells, prepare cells for assaying and assay the de novo pyrimidine biosynthetic enzymes. This will allow a student to understand the basic principles of biochemistry as it relates to enzymes.

Carbamoyl phosphate + L-Aspartate

pyrB↓

Carbamoyl aspartate

pyrC↓

Dihydroorotic acid

pyrD↓

Orotic acid + PRPP

pyrE↓

OMP

pyrF↓

UMP