HDV ribozyme activity in monovalent cations.

Anne T Perrotta; Michael D Been

doi:10.1021/bi061215+

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PubMed · 16981696

HDV ribozyme activity in monovalent cations.

Anne T Perrotta·Michael D Been

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Abstract

Activity of the two ribozymes from hepatitis delta virus in monovalent salts was examined and compared to activity in Mg2+. Both ribozymes self-cleaved in high concentrations of monovalent cations, and an active site cytosine was required for cleavage activity under those conditions. Cleavage rates were 30-50-fold higher for reactions in LiCl than for reactions in NaCl or NH4Cl, and a thio effect indicated that chemistry was rate-determining for cleavage of the HDV genomic ribozyme in LiCl. Still, in LiCl, there was a more than 100-fold increase in the rate when MgCl2 was included in the reaction. However, the pH-rate profiles for the reactions in LiCl with and without MgCl2 were both bell-shaped with the pH optima in the neutral range. These findings support the idea that monovalent cations can partially substitute for divalent metal ions in the HDV ribozymes, although a divalent metal ion is more effective in supporting catalysis. The absence of a dramatic change in the general shape of pH-rate profiles in LiCl, relative to the profile for reactions including Mg2+, is in contrast to earlier data for the reactions in NaCl and limits our interpretation of the specific role played by the divalent metal ion in the catalytic mechanism.

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Base Sequence Binding Sites Catalysis Cations, Divalent Cations, Monovalent Cytosine Genome, Viral Hepatitis Delta Virus Hydrogen-Ion Concentration Kinetics Magnesium Molecular Sequence Data Nucleic Acid Conformation Phosphates Quaternary Ammonium Compounds RNA, Catalytic Journal Article Research Support, N.I.H., Extramural

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Anne T Perrotta, Michael D Been. 2006-09-26. HDV ribozyme activity in monovalent cations.. https://doi.org/10.1021/bi061215%2B

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