Binding of 2′,3′-Cyclic Nucleotide Monophosphates to Bacterial Ribosomes Inhibits Translation

The intracellular small molecules 2′,3′-cyclic
nucleotide
monophosphates (2′,3′-cNMPs) have recently been rediscovered
within both prokaryotes and eukaryotes. Studies in bacteria have demonstrated
that 2′,3′-cNMP levels affect bacterial phenotypes,
such as biofilm formation, motility, and growth, and modulate expression
of numerous genes, suggesting that 2′,3′-cNMP levels
are monitored by cells. In this study, 2′,3′-cNMP-linked
affinity chromatography resins were used to identify Escherichia
coli proteins that bind 2′,3′-cNMPs, with the
top hits including all of the ribosomal proteins, and to confirm direct
binding of purified ribosomes. Using in vitro translation
assays, we have demonstrated that 2′,3′-cNMPs inhibit
translation at concentrations found in amino acid-starved cells. In
addition, a genetically encoded tool to increase cellular 2′,3′-cNMP
levels was developed and was demonstrated to decrease E. coli growth rates. Taken together, this work suggests a mechanism for
2′,3-cNMP levels to modulate bacterial phenotypes by rapidly
affecting translation.