Properties of an in vitro selected Pb2+ cleavage motif.
The addition of Pb2+ to a small RNA molecule consisting of an asymmetric internal loop of six nucleotides results in site-specific cleavage followed by hydrolysis of the 2',3'-cyclic phosphate intermediate [Pan, T., & Uhlenbeck, O.C. (1992) Nature 358, 560-563]. Here we show that the reaction is highly specific for Pb2+ and the cleavage rate increases exponentially with pH from 5.5 to 7.0, both in the presence and in the absence of Mg2+. This suggests that the reaction mechanism involves Pb2+ hydroxide acting as a base. Several sequence variants of the RNA are found to be equally active in both steps of the reaction, suggesting that they fold into a similar structure.
Pan
T
T
Department of Chemistry and Biochemistry, University of Colorado at Boulder 80309-0215.
Dichtl
B
B
Uhlenbeck
O C
OC
D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000737:chemistry / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism; D012360:RNA, Transfer, Phe / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012641:Selection, Genetic; D013329:Structure-Activity Relationship
D002413:Cations, Divalent; D009843:Oligoribonucleotides; D012330:RNA, Double-Stranded; D012360:RNA, Transfer, Phe; D007854:Lead