Ribosome-Catalyzed Peptide-Bond Formation with an A-Site Substrate Covalently Linked to 23S Ribosomal RNA

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Science  10 Apr 1998:
Vol. 280, Issue 5361, pp. 286-289
DOI: 10.1126/science.280.5361.286

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In the ribosome, the aminoacyl–transfer RNA (tRNA) analog 4-thio-dT-p-C-p-puromycin crosslinks photochemically with G2553 of 23S ribosomal RNA (rRNA). This covalently linked substrate reacts with a peptidyl-tRNA analog to form a peptide bond in a peptidyl transferase–catalyzed reaction. This result places the conserved 2555 loop of 23S rRNA at the peptidyl transferase A site and suggests that peptide bond formation can occur uncoupled from movement of the A-site tRNA. Crosslink formation depends on occupancy of the P site by a tRNA carrying an intact CCA acceptor end, indicating that peptidyl-tRNA, directly or indirectly, helps to create the peptidyl transferase A site.

  • * Present address: Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.

  • To whom correspondence should be addressed. E-mail: harry{at}

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