Small Ribozymes

Abstract

The course of history is strewn with revolutionary discoveries, which have changed the scientific views or dogmas of the period and stimulated subsequent research. An example is the landmark discovery, in the laboratories of Altman and Cech in the early 1980s, of RNA molecules with the ability to catalyze phosphodiester bond cleavage in the absence of proteins (Kruger et al. 1982; Guerrier-Takada et al. 1983). These findings gave the first indication that in addition to carrying genetic information, RNA molecules were also capable of catalyzing chemical reactions. RNA may therefore hold the key to understanding the origin of life, and the present-day cooperation between DNA, RNA, and proteins may have evolved out of a purely RNA world (Gesteland and Atkins 1993). This notion is consistent with the large variety of ribonucleotides that have been identified in RNA (Limbach et al. 1994) which are thought to be leftovers from the more archaic activities of RNA molecules. Since the initial publications of ribozyme activity, other naturally occurring ribozyme motifs have been discovered. In addition, the advent of in vitro selection has expanded the number of chemical reactions, thought previously to be performed by proteins, that can be catalyzed by RNA molecules (Gold et al. 1995). This technique has rapidly expanded our knowledge of RNA motifs capable of supporting catalytic activity and has led to an explosion of data regarding the structural and functional diversity of RNA.

In addition to fulfilling a scientific curiosity, the findings thus far also indicate that RNA holds...