Pré-Publication, Document De Travail Année : 2020

The final step of 40S ribosomal subunit maturation is controlled by a dual key lock

Ramtin Shayan
  • Fonction : Auteur
Christian Montellese
  • Fonction : Auteur
Dana Rinaldi
  • Fonction : Auteur
Natacha Larburu
  • Fonction : Auteur
Carole Pichereaux
  • Fonction : Auteur
Simon Lebaron
Marie-Françoise O'Donohue
Ulrike Kutay
Julien Marcoux
  • Fonction : Auteur
Pierre-Emmanuel Gleizes
Celia Plisson-Chastang

Résumé

Preventing premature interaction of preribosomes with the translation apparatus is essential to translation accuracy. Hence, the final maturation step releasing functional 40S ribosomal subunits, namely processing of the 18S ribosomal RNA 3′ end, is safeguarded by protein DIM2, which both interacts with the endoribonuclease NOB1 and masks the rRNA cleavage site. To elucidate the control mechanism that unlocks NOB1 activity, we performed cryo-EM analysis of late human pre-40S particles purified using a catalytically-inactive form of ATPase RIO1. These structures, together with in vivo and in vitro functional analyses, support a model in which ATPloaded RIO1 cooperates with ribosomal protein RPS26/eS26 to displace DIM2 from the 18S rRNA 3′ end, thereby triggering final cleavage by NOB1; release of ADP then leads to RIO1 dissociation from the 40S subunit. This dual key lock mechanism requiring RIO1 and RPS26 guarantees the precise timing of pre-40S particle conversion into translation-competent ribosomal subunits.

Preventing premature interaction of preribosomes with the translation apparatus is essential to translation accuracy. Hence, the final maturation step releasing functional 40S ribosomal subunits, namely processing of the 18S ribosomal RNA 3′ end, is safeguarded by protein DIM2, which both interacts with the endoribonuclease NOB1 and masks the rRNA cleavage site. To elucidate the control mechanism that unlocks NOB1 activity, we performed cryo-EM analysis of late human pre-40S particles purified using a catalytically-inactive form of ATPase RIO1. These structures, together with in vivo and in vitro functional analyses, support a model in which ATPloaded RIO1 cooperates with ribosomal protein RPS26/eS26 to displace DIM2 from the 18S rRNA 3′ end, thereby triggering final cleavage by NOB1; release of ADP then leads to RIO1 dissociation from the 40S subunit. This dual key lock mechanism requiring RIO1 and RPS26 guarantees the precise timing of pre-40S particle conversion into translation-competent ribosomal subunits.

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hal-02989653 , version 1 (07-11-2020)

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Laura Plassart, Ramtin Shayan, Christian Montellese, Dana Rinaldi, Natacha Larburu, et al.. The final step of 40S ribosomal subunit maturation is controlled by a dual key lock. 2020. ⟨hal-02989653⟩

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