Pyrrolysine supply and demand shapes the translational landscape in Methanosarcina acetivorans.

High pyrrolysine demand in Methanosarcina acetivorans increases Pyl-tRNA acylation and reduces ribosome dwell time at UAG codons, affecting translation dynamics.

• Why it matters: Understanding how organisms regulate the decoding of ambiguous stop codons like UAG is crucial for insights into genetic code expansion and translation control mechanisms in archaea.
• What they did: The study combined RNA sequencing, tRNA charging analysis, and ribosome profiling to examine translation under varying pyrrolysine demands, focusing on Pyl-tRNA levels and ribosome behavior.
• The result: Findings reveal that pyrrolysine demand modulates tRNA charging and elongation speed, with high demand decreasing dwell time but increasing ribosome collisions, illuminating cellular responses to genetic code ambiguity.