CRL2 aids elimination of truncated selenoproteins produced by failed UGA/Sec decoding

• Autores: Hsiu-Chuan Lin, Szu-Chi Ho, Yi-Yun Chen
• Localización: Science, ISSN 0036-8075, Vol. 349, Nº 6243, 2015, págs. 91-95
• Idioma: inglés
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• Resumen

  • Selenocysteine (Sec) is translated from the codon UGA, typically a termination signal. Codon duality extends the genetic code; however, the coexistence of two competing UGA-decoding mechanisms immediately compromises proteome fidelity. Selenium availability tunes the reassignment of UGA to Sec. We report a CRL2 ubiquitin ligase–mediated protein quality-control system that specifically eliminates truncated proteins that result from reassignment failures. Exposing the peptide immediately N-terminal to Sec, a CRL2 recognition degron, promotes protein degradation. Sec incorporation destroys the degron, protecting read-through proteins from detection by CRL2. Our findings reveal a coupling between directed translation termination and proteolysis-assisted protein quality control, as well as a cellular strategy to cope with fluctuations in organismal selenium intake.