Bacterial ribosome–SpeFL complex (None formally established; sometimes referenced as "ribosome–SpeFL" or "SpeFL–ribosome complex")

The bacterial ribosome–SpeFL complex refers to a regulatory state formed when ornithine is captured by the translating bacterial ribosome, causing stalling during translation of the nascent peptide SpeFL. SpeFL is a sensor peptide that binds ornithine in a highly selective manner, forming a compact fold that obstructs the ribosomal exit tunnel and blocks release factor activity. This stalling promotes transcriptional antitermination and upregulates the expression of the polyamine biosynthetic enzyme ornithine decarboxylase (SpeF), thereby increasing polyamine synthesis. The system is found in γ-proteobacteria and plays a crucial role in adaptation, stress response, and microbial virulence. The structure has been resolved by cryo-electron microscopy, revealing the molecular details of ornithine sensing and peptide-ribosome interaction. This complex is not a classical drug target but provides insight into bacterial metabolic regulation and potential strategies for antimicrobial intervention.

Other names

Ribosome–SpeFL complexSpeFL-stalled ribosomeOrnithine sensing ribosome–SpeFL complex

Not applicable to the SpeFL complex directly; antibiotic mechanisms for ribosome include inhibition of protein synthesis (ribosome inhibition).