Growth inhibition of a <i>Staphylococcus aureus</i> aminopterin-derived thymineless mutant by exogenous nucleosides in the presence of thymine

Abstract

Adenosine partially inhibits growth of Staphylococcus aureus Wood 46 parent strain because of feedback inhibition, whereas uridine has no effect. However, adenosine and uridine completely block the growth of an aminopterin-derived thymineless mutant of the Wood 46 strain in the presence of thymine; the site of inhibition seems to be located at the level of thymidine synthesis from thymine, since (1) normal growth is restored when thymidine is used instead of thymine; (2) deoxyuridine monophosphate cannot be converted into thymidine monophosphate by interconversion, thymidylate synthetase being inoperative in the thymineless auxotroph.