A new metal ion interaction in the Tetrahymena ribozyme reaction revealed by double sulfur substitution.
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.
Yoshida
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Department of Biochemistry and Molecular Biology, Howard Hughes Medical Institute, The University of Chicago, Illinois 60637, USA.
Sun
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S
Piccirilli
J A
JA
D000818:Animals; D008345:Manganese / Q000737:chemistry / Q000378:metabolism; D008670:Metals / Q000737:chemistry / Q000378:metabolism*; D009946:Organothiophosphorus Compounds / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D006163:Ribonuclease T1 / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013455:Sulfur / Q000737:chemistry*; D013768:Tetrahymena / Q000235:genetics*; D013873:Thionucleotides / Q000737:chemistry; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
D008670:Metals; D009946:Organothiophosphorus Compounds; D016337:RNA, Catalytic; D013873:Thionucleotides; D008345:Manganese; D013455:Sulfur; D006163:Ribonuclease T1; D015032:Zinc; D010100:Oxygen