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ID: 174925.0, MPI für molekulare Genetik / Ribosome Research Groups
Molecular mimicry in the decoding of translational stop signals
Authors:Poole, Elizabeth S.; Askarian-Amiri, Marjan E.; Major, Louise L.; McCaughan, Kim K.; Scarlett, Debbie-Jane; Wilson, Daniel N.; Tate, Warren P.
Place of Publication:Amsterdam [et al]
Publisher:Academic Press, an imprint of Elsevier
Date of Publication (YYYY-MM-DD):2003
Title of Book:Progress in nucleic acid research and molecular biology
Start Page:83
End Page:121
Full Name of Book-Editor(s):Moldave, Kivie
Title of Series:Progress in nucleic acid and molecular biology
Full Name(s) of Series Editor(s):Moldave, Kivie
Copyright:© 2003 Elsevier Inc.
Review Status:not specified
Audience:Experts Only
Abstract / Description:The structures of the ribosome and its subunits are now available at atomic detail, as well as those of several factors that bind to its active center. Of particular interest are the protein release factors that decode stop signals. In contrast to the codons specifying the different amino acids, the stop signals are not decoded by RNA molecules, the tRNAs. The tRNA analogue hypothesis (1994) for the decoding of stop signals was proposed to explain how the release factors might mimic a tRNA to span the decoding site of the small subunit and the enzyme center of the large subunit of the ribosome. The specific term "molecular mimicry" was applied soon after to include proteins or their domains that enter the tRNA binding sites on the ribosome. The solution crystal structures of the two release factors already solved (one eubacterial and one eukaryotic), although quite distinct in their folds, each resembles the shape of a tRNA. The eukaryotic factor, like a tRNA, seems to have specific motifs at the tips of two of its domains that interact with the decoding site and the enzyme center as predicted in the tRNA analogue model. Biochemical and genetic studies had identified two analogous motifs in the bacterial factors, but these are quite close together in the solution structure, suggesting a major conformational change may take place when the factor binds to the ribosome. Indeed, reconstructed cryoelectron microscopic images support an unfolding of the structure. A second class of release factor functions as a translational G-protein in the same manner as the two elongation factors and forms part of the termination mimicry complex. Undoubtedly, the molecular mimicry concept will be refined as the conformational changes that take place in the active center of the ribosome and in the proteins that bind to it are better understood.
External Publication Status:published
Document Type:InBook
Communicated by:Ribosome Group
Affiliations:MPI für molekulare Genetik
External Affiliations:Department of Biochemistry, University of Otago, Dunedin, New Zealand
Identifiers:ISBN:0-12-540074-8 [ID No:1]
ISSN:0079-6603 [ID No:2]
DOI:10.1016/S0079-6603(03)01011-0 [ID No:3]
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