Cameron, D.E. & Collins, J.J. Nat. Biotechnol. 32, 1276–1281 (2014).

Tuning protein levels post-translationally in bacteria is challenging. Cameron and Collins developed a new strategy for targeting any protein in Escherichia coli for degradation using a modified transfer-messenger RNA (tmRNA) system. tmRNAs add a protein-degradation tag ('pdt') to targeted proteins that subjects them to degradation. The Mesoplasma florum tmRNA system is unique because the pdt is degraded by a specific protease called Lon but not by cellular proteases in E. coli. By tagging genes with this pdt and coexpressing Lon, the researchers were able to tunably degrade target proteins. The team then tagged 238 of the 305 essential genes in E. coli to create the Essential Protein Degradation library. They show that modulation of essential protein levels can be used to discover antibiotic targets and to identify new targets for antibiotic development.