The incorporation of pyrimidine nucleotide precursors into Helicobacte
r pylori and the activities of enzymes involved in their synthetic pat
hways were investigated by radioactive tracer analysis and P-31 nuclea
r magnetic resonance spectroscopy. The bacterium was found to take up
aspartate and bicarbonate and to incorporate carbon atoms from these p
recursors into its genomic DNA. Orotate, an intermediate of de novo py
rimidine biosynthesis, and uracil and uridine, precursors for pyrimidi
ne pathways, were also incorporated by the micro-organism. Radiolabell
ed substrates were used to assess the activities of aspartate transcar
bamoylase, orotate phosphoribosyltransferase, orotidylate decarboxylas
e, CTP synthetase, uracil phosphoribosyltransferase, thymidine kinase
and deoxycytidine kinase in bacterial lysates. The study provided evid
ence for the presence in H. pylori of an operational de nova pathway,
and a less active salvage pathway for the biosynthesis of pyrimidine n
ucleotides.