Elucidation of Sequence Constraints for Protein Folding on the Ribosome

Mutational scanning of Escherichia coli dihydrofolate reductase (DHFR) on stalled ribosomes shows 9,480 mutations modulate cotranslational folding, with vulnerability concentrated in specific domain contacts.

• Why it matters: Cotranslational folding may restrict which sequences can fold correctly, but the sequence-level constraints imposed by ribosome-associated folding remain unclear.
• What they did: The study paired a fluorogenic arrest peptide sensor with deep mutational scanning to test how 9,480 DHFR mutations affect folding efficiency on stalled ribosomes in live cells, controlling for variant abundance.
• The result: Overall mutational trends track computational native-fold free-energy changes, yet detailed patterns pinpoint sensitivity in the adenosine binding domain’s central contacts and the C-terminal {beta}-strands of the discontinuous loop domain, implying ribosome-specific evolutionary constraints.

AI summary of the abstract · may contain errors · not medical advice · read the paper.