Structure of a protein L23-RNA complex located at the A-site domain of the ribosomal peptidyl transferase centre

AbstractArfA rescues ribosomes stalled on truncated mRNAs by recruiting the 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, hitherto unobserved in 70S termination complexes. 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.

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Antibiotic Action on the Ribosomal Peptidyl Transferase Centre

Drug Receptor Interactions in Antimicrobial Chemotherapy - Topics in Infectious Diseases ◽

10.1007/978-3-7091-8405-9_14 ◽

1975 ◽

pp. 193-216 ◽

Cited By ~ 2

Author(s):

D. Vazquez ◽

M. Barbacid ◽

R. Fernandez-Muñoz

Keyword(s):

Peptidyl Transferase ◽

Antibiotic Action ◽

Peptidyl Transferase Centre

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The Involvement of Sulphydryl Groups in the Peptidyl Transferase Centre of Eukaryotic Ribosomes

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1975.tb09806.x ◽

1975 ◽

Vol 50 (2) ◽

pp. 317-323 ◽

Cited By ~ 16

Author(s):

Luis CARRASCO ◽

David VAZQUEZ

Keyword(s):

Peptidyl Transferase ◽

Sulphydryl Groups ◽

Peptidyl Transferase Centre

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Ribosome crystallography: catalysis and evolution of peptide-bond formation, nascent chain elongation and its co-translational folding

Biochemical Society Transactions ◽

10.1042/bst0330488 ◽

2005 ◽

Vol 33 (3) ◽

pp. 488-492 ◽

Cited By ~ 12

Author(s):

A. Bashan ◽

A. Yonath

Keyword(s):

Bond Formation ◽

Peptide Bond ◽

Trigger Factor ◽

Chain Elongation ◽

Peptide Bond Formation ◽

Peptidyl Transferase ◽

Chemical Catalysis ◽

Nascent Chain ◽

Peptidyl Transferase Centre ◽

Folding Space

A ribosome is a ribozyme polymerizing amino acids, exploiting positional- and substrate-mediated chemical catalysis. We showed that peptide-bond formation is facilitated by the ribosomal architectural frame, provided by a sizable symmetry-related region in and around the peptidyl transferase centre, suggesting that the ribosomal active site was evolved by gene fusion. Mobility in tunnel components is exploited for elongation arrest as well as for trafficking nascent proteins into the folding space bordered by the bacterial chaperone, namely the trigger factor.

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