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Mechanism of ribosome rescue by ArfA and RF2.

ABSTRACT: ArfA rescues ribosomes stalled on truncated mRNAs by recruiting release factor RF2, which normally binds stop codons to catalyze peptide release. We report two 3.2 Å resolution cryo-EM structures - determined from a single sample - of the 70S ribosome with ArfA•RF2 in the A site. In both states, the ArfA C-terminus occupies the mRNA tunnel downstream of the A site. One state contains a compact inactive RF2 conformation. Ordering of the ArfA N-terminus in the second state rearranges RF2 into an extended conformation that docks the catalytic GGQ motif into the peptidyl-transferase center. Our work thus reveals the structural dynamics of ribosome rescue. The structures demonstrate how ArfA 'senses' the vacant mRNA tunnel and activates RF2 to mediate peptide release without a stop codon, allowing stalled ribosomes to be recycled.

SUBMITTER: Demo G

PROVIDER: S-EPMC5378476 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Mechanism of ribosome rescue by ArfA and RF2.

Demo Gabriel G Svidritskiy Egor E Madireddy Rohini R Diaz-Avalos Ruben R Grant Timothy T Grigorieff Nikolaus N Sousa Duncan D Korostelev Andrei A AA

eLife 20170316

ArfA rescues ribosomes stalled on truncated mRNAs by recruiting release factor RF2, which normally binds stop codons to catalyze peptide release. We report two 3.2 Å resolution cryo-EM structures - determined from a single sample - of the 70S ribosome with ArfA•RF2 in the A site. In both states, the ArfA C-terminus occupies the mRNA tunnel downstream of the A site. One state contains a compact inactive RF2 conformation. Ordering of the ArfA N-terminus in the second state rearranges RF2 into an e ...[more]

PMID: 28300532

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Structural basis of co-translational quality control by ArfA and RF2 bound to ribosome.

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tmRNA regulates synthesis of the ArfA ribosome rescue factor.

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Extensive ribosome and RF2 rearrangements during translation termination.

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Project description: Not available

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