Role of divalent metal ions in the hammerhead RNA cleavage reaction.

摘要: A hammerhead self-cleaving domain composed of two oligoribonucleotides was used to study the role divalent metal ions in cleavage reaction. Cleavage rates were measured as a function MgCl2, MnCl2, and CaCl2 concentration absence or presence spermine. In spermine, rate vs ion curves are broader, lower concentrations necessary for catalytic activity. This suggests that spermine can promote proper folding one more required Six additional tested their ability support cleavage. rapid observed with Co2+ while very slow occurred Sr2+ Ba2+. No detectable specific Cd2+, Zn2+, Pb2+. However, 0.5 mM Zn2+ increased, indicating these three could not they able stimulate These results suggest certain either participate directly mechanism specifically involved stabilizing tertiary structure hammerhead. Additionally, an altered specificity when unique phosphorothioate linkage inserted at site. The substitution sulfur nonbridging oxygen atom substantially reduced affinity important Mg2+ efficient contrast, reaction proceeds normally Mn2+, presumably due its coordinate both sulfur.(ABSTRACT TRUNCATED AT 250 WORDS)