Characteristics of Ribonuclease P from Various Organisms

Excerpt

Ribonuclease P (RNase P) is an endoribonuclease required for the maturation of the 5′ termini of tRNAs from their precursors (for review, see Altman et al. 1986). This enzyme, which engages in a single cleavage event to generate a 5′ phosphate in its tRNA products in vivo and in vitro, has been best characterized in extracts of Escherichia coli. It has a catalytic RNA subunit (M1 RNA) and a protein subunit (C5 protein; Guerrier-Takada et al. 1983). Under certain conditions in vitro, the RNA subunit alone can carry out the cleavage of tRNA precursors. This reaction, catalyzed by M1 RNA, has all the features of a true enzymatic reaction, and its mechanism differs from those of the reactions governed by other RNA enzymes (Table 1). Although RNase P generates the same end groups in its products as do group I self-splicing introns during the cleavage step performed by these introns,...