Structural highlights
Publication Abstract from PubMed
Elevated levels of the free amino acid L-tryptophan (L-Trp) trigger expression of the tryptophanase tnaCAB operon in E. coli. Activation depends on tryptophan-dependent ribosomal stalling during translation of the upstream TnaC peptide. Here, we present a cryoelectron microscopy (cryo-EM) reconstruction at 3.8 A resolution of a ribosome stalled by the TnaC peptide. Unexpectedly, we observe two L-Trp molecules in the ribosomal exit tunnel coordinated within composite hydrophobic pockets formed by the nascent TnaC peptide and the tunnel wall. As a result, the peptidyl transferase center (PTC) adopts a distinct conformation that precludes productive accommodation of release factor 2 (RF2), thereby inducing translational stalling. Collectively, our results demonstrate how the translating ribosome can act as a small molecule sensor for gene regulation.
Molecular Basis for the Ribosome Functioning as an L-Tryptophan Sensor.,Bischoff L, Berninghausen O, Beckmann R Cell Rep. 2014 Oct 7. pii: S2211-1247(14)00779-7. doi:, 10.1016/j.celrep.2014.09.011. PMID:25310980[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Bischoff L, Berninghausen O, Beckmann R. Molecular Basis for the Ribosome Functioning as an L-Tryptophan Sensor. Cell Rep. 2014 Oct 7. pii: S2211-1247(14)00779-7. doi:, 10.1016/j.celrep.2014.09.011. PMID:25310980 doi:http://dx.doi.org/10.1016/j.celrep.2014.09.011
