RNase P RNA-mediated Cleavage

Metal(II)-induced hydrolysis of RNA produce products with 5'-hydroxyls and 2';3'-cyclic phosphates at the ends. Ribozymes are RNA molecules that act as catalysts. Some ribozymes that cleave RNA also generate 5-hydroxyls and 2';3-cyclic phosphates whereas others produces 5-phosphates and 5'-hydroxyls at the ends of the cleavage products. RNase P is an essential endoribonuclease involved in RNA processing. The catalytic RNA subunit or RNase P is a trans-acting ribozyme that cleaves various RNA substrates in vitro generating 5'-phosphates and Y-hydroxyls as cleavage products. The activity depends on the presence of metal(II) ions such as Mg2+. RNase P RNA has therefore to facilitate a nucleophilic attack that generates the correct product ends and prevent metal(II)-induced hydrolysis of the RNA substrate. In this review, we will discuss our current understanding of the interactions between RNase P RNA and its substrate, role of specific residues with respect to catalysis and positioning of functionally important Mg2+ at and in the vicinity of the cleavage site that ensures that products with correct ends are generated. Moreover, we will discuss the composition of RNase P and its RNA subunit in an evolutionary perspective. (C) 2009 IUBMB