Ornithine sensing by the bacterial ribosome

Herrero del Valle, A., Seip, B., Cervera-Marzal, I., Sacheau, G., Seefeldt, A.C., Innis, C.A. (2020). Ornithine capture by a translating ribosome controls bacterial polyamine synthesis. Nat Microbiol  5, 554–561.

PDB entries: 6TBV, 6TC3

EMDB entries: EMD-10458, EMD-10453

We identify a new arrest peptide, SpeFL, and determine the mechanism by which it controls the expression of speF, leading to polyamine production in certain gamma-proteobacteria. We propose a model whereby ornithine, a small molecule with no intrinsic affinity for the ribosome, is captured by a ribosome translating speFL, eventually leading to ribosome stalling via a kinetically-controlled process.