Transport of Pyrimidine Nucleosides in Cells of Escherichia coli K 12

Abstract

The transport of pyrimidine nucleosides into cells of Escherichia coli has been investigated in mutant strains which cannot metabolize these nucleosides. Such cells transport and concentrate pyrimidine nucleosides several hundred‐fold. The transport is inhibited by energy poisons and by sulfhydryl reagents. Pyrimidine nucleosides compete mutually for transport. Adenosine is also a strong competitor while guanosine and inosine are weak competitors. The rate of pyrimidine nucleoside transport is shown to be under control of the cytR and deoR gene products, which are also known to regulate the synthesis of nucleoside‐catabolizing enzymes. The transport system is repressed by growth on glucose, as is the synthesis of the enzymes. Copyright © 1975, Wiley Blackwell. All rights reserved