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  • Title: A new metal ion interaction in the Tetrahymena ribozyme reaction revealed by double sulfur substitution.
    Author: Yoshida A, Sun S, Piccirilli JA.
    Journal: Nat Struct Biol; 1999 Apr; 6(4):318-21. PubMed ID: 10201397.
    Abstract:
    The Tetrahymena ribozyme is a metalloenzyme that catalyzes cleavage of oligonucleotide substrates by phosphoryl transfer. Thiophilic metal ions such as Mn2+, Zn2+ or Cd2+ rescue the >10(3)-fold inhibitory effect of sulfur substitution of the 3'-oxygen leaving group but do not effectively rescue the effect of sulfur substitution of the nonbridging pro-Sp phosphoryl oxygen. We now show that the latter effect can be fully rescued by Zn2+ or Cd2+ using a phosphorodithioate substrate, in which both the 3'-oxygen and the pro-Sp oxygen are simultaneously substituted with sulfur. These results provide the first functional evidence that metallophosphotransferases can mediate catalysis via metal ion coordination to both the leaving group and a nonbridging oxygen of the scissile phosphate.
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