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Structural insights into peptide bond formation

By Jeffrey L. Hansen, T. Martin Schmeing, Peter B. Moore and Thomas A. Steitz

Abstract

The large ribosomal subunit catalyzes peptide bond formation and will do so by using small aminoacyl- and peptidyl-RNA fragments of tRNA. We have refined at 3-Å resolution the structures of both A and P site substrate and product analogues, as well as an intermediate analogue, bound to the Haloarcula marismortui 50S ribosomal subunit. A P site substrate, CCA-Phe-caproic acid–biotin, binds equally to both sites, but in the presence of sparsomycin binds only to the P site. The CCA portions of these analogues are bound identically by either the A or P loop of the 23S rRNA. Combining the separate P and A site substrate complexes into one model reveals interactions that may occur when both are present simultaneously. The α-NH(2) group of an aminoacylated fragment in the A site forms one hydrogen bond with the N3 of A2486 (2451) and may form a second hydrogen bond either with the 2′ OH of the A-76 ribose in the P site or with the 2′ OH of A2486 (2451). These interactions position the α amino group adjacent to the carbonyl carbon of esterified P site substrate in an orientation suitable for a nucleophilic attack

Topics: Biological Sciences
Publisher: The National Academy of Sciences
Year: 2002
DOI identifier: 10.1073/pnas.172404099
OAI identifier: oai:pubmedcentral.nih.gov:129327
Provided by: PubMed Central
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