Chaperone-directed ribosome repair after oxidative damage

Ribosomes are essential for translation and quality control, yet how cells maintain their integrity under oxidative stress was previously unknown. This study reveals a chaperone-directed mechanism that repairs, rather than degrades, oxidatively damaged ribosomes. The authors identify cysteine residues in ribosomal proteins Rps26 and Rpl10 as primary oxidation targets that impair ribosome function. Upon oxidation, these proteins are released from ribosomes by their cognate chaperones, Tsr2 and Sqt1, which mediate their exchange with newly synthesized counterparts. This selective repair pathway restores functional ribosomes and sustains translation during stress. Loss of Tsr2- or Sqt1-mediated exchange compromises cell growth, particularly under oxidative conditions, demonstrating the physiological significance of ribosome repair. These findings redefine ribosome quality control as a dynamic process encompassing targeted protein replacement, providing a mechanistic link between redox homeostasis, translation fidelity, and cellular resilience to oxidative stress.