A Double Dose of Trp Regulation

Abstract

Amino acid synthesis is tightly controlled in bacteria by a system in which the amino acids themselves, as well as their corresponding transfer RNAs (tRNAs), regulate production. For example, in Bacillus subtilis , the mechanism for regulating tryptophan (Trp) synthesis involves an antiterminator protein called TRAP, which is activated by Trp. However, TRAP activity is antagonized by a protein called anti-TRAP (AT), where the synthesis of AT is induced by uncharged tRNA Trp . Chen and Yanofsky now show another level of regulation for the Trp operon in which uncharged tRNA Trp also regulates the translation of AT through tandem Trp codons in a leader peptide coding sequence. This mechanism is somewhat reminiscent of the classical Trp attenuation system in Escherchia coli ; however, the leader peptide in B. subtilis exerts its effect at the level of translation instead of transcription termination, as seen in E. coli . The authors term the B. subtilis system "regulatory sophistication" because it shows both transcriptional and translational regulation of AT in response to tRNA Trp . G. Chen, C. Yanofsky, Tandem transcription and translation regulatory sensing of uncharged tryptophan tRNA. Science 301 , 211-213 (2003). [Abstract] [Full Text]