Multivalent weak contacts shape chaperone-nascent protein interactions.

Trigger factor interacts with ribosome-bound nascent proteins through multivalent, dynamic, weak contacts that increase non-monotonically with chain length.

• Why it matters: Understanding how chaperones like trigger factor engage with emerging proteins is crucial for revealing mechanisms that prevent misfolding during synthesis, a key aspect of cellular proteostasis.
• What they did: The study used single-molecule fluorescence and optical tweezers to observe trigger factor interactions with ribosome-bound nascent chains of varying lengths, analyzing dwell times and binding behavior.
• The result: Trigger factor binds via multiple weak, dynamic interactions that evolve during polypeptide elongation, and mechanical force disrupts this binding, suggesting a model that stabilizes nascent proteins while allowing conformational sampling.