ENZYMATIC CLEAVAGE OF RNA BY RNA

Biological catalysis by RNA—this discovery at the beginning of the 1980s was sensational, since it had been assumed that only proteins were capable of functioning as biocatalysts. Sidney Altman studied the enzyme ribonuclease P, which is composed of RNA and protein subunits, and found conditions under which the RNA component could catalyze the formation of mature tRNA in the absence of protein. Thomas R. Cech discovered the phenomenon of self‐splicing rRNA in Tetrahymena thermophila. This rRNA catalyzes the consecutive transesterification of specific phosphodiester groups in its nucleotide sequence and thereby the excision of an intervening sequence (IVS; see picture below) and ligation of the remaining rRNA molecule. The work of Altman and Cech, for which they were awarded the Nobel Prize in chemistry in 1989, upset a paradigm in biochemistry. (Figure Presented.) Copyright © 1990 by VCH Verlagsgesellschaft mbH, Germany