An energy transfer equilibrium between two identical copies of a ribosome-bound fluorescent transfer RNA analogue: Implications for the possible structure of codon-anticodon complexes

Robert H Fairclough, Charles R. Cantor

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

When yeast tRNAPf Phe, a derivative of tRNAPhe in which proflavine replaces the Y base, is bound simultaneously to both the peptidyl and aminoacyl sites of a 70 S Escherichia coli ribosome, there is a rapid mutual energy transfer between the two bound tRNAs. Analysis of this energy transfer yields an upper limit for the proflavine-proflavine distance of 20 Å. It also allows an unequivocal measurement of the emission spectrum of tRNAPf Phe bound at the aminoacyl site. In the presence of message this spectrum is very different from that seen in the peptidyl site, implying that in the two sites the hypermodified bases exist in significantly different environments. The rapid energy transfer leads to some loss of fluorescence anisotropy. This can be analyzed to obtain an estimate of the angle between the two proflavines: 28 ° ± 10 ° or 152 ° ± 10 °. Taken together all of these results place severe constraints on possible models of codon-anticodon complexes. The mutual energy transfer seen and analyzed on the ribosome is a convenient aspect of fluorescence spectroscopy, and it is one that should see broad application where multiple copies of a fluorescent ligand interact on a macromolecular substrate.

Original languageEnglish (US)
Pages (from-to)587-601
Number of pages15
JournalJournal of Molecular Biology
Volume132
Issue number4
DOIs
StatePublished - Aug 25 1979
Externally publishedYes

ASJC Scopus subject areas

  • Virology

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