Three metal ions at the active site of the Tetrahymena group I ribozyme.

نویسندگان

  • S o Shan
  • A Yoshida
  • S Sun
  • J A Piccirilli
  • D Herschlag
چکیده

Metal ions are critical for catalysis by many RNA and protein enzymes. To understand how these enzymes use metal ions for catalysis, it is crucial to determine how many metal ions are positioned at the active site. We report here an approach, combining atomic mutagenesis with quantitative determination of metal ion affinities, that allows individual metal ions to be distinguished. Using this approach, we show that at the active site of the Tetrahymena group I ribozyme the previously identified metal ion interactions with three substrate atoms, the 3'-oxygen of the oligonucleotide substrate and the 3'- and 2'-moieties of the guanosine nucleophile, are mediated by three distinct metal ions. This approach provides a general tool for distinguishing active site metal ions and allows the properties and roles of individual metal ions to be probed, even within the sea of metal ions bound to RNA.

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عنوان ژورنال:
  • Proceedings of the National Academy of Sciences of the United States of America

دوره 96 22  شماره 

صفحات  -

تاریخ انتشار 1999