Properties of an in vitro selected Pb super(2+) cleavage motif

• Published in: Biochemistry (Easton) Vol. 33; no. 32; pp. 9561 - 9565
• Main Authors: Pan, T, Dichtl, B, Uhlenbeck, O C
• Format: Journal Article
• Language: English
• Published: 01.01.1994
• ISSN: 0006-2960

The addition of Pb super(2+) 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. Here we show that the reaction is highly specific for Pb super(2+) and the cleavage rate increases exponentially with pH from 5.5 to 7.0, both in the presence and in the absence of Mg super(2+). This suggests that the reaction mechanism involves Pb super(2+) 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.