Journal Article: Guerrier-Takada, C. (Working with Altman, S.) (1983) "The RNA Moiety of Ribonuclease P is the Catalytic Subunit of the Enzyme." Cell 35: 849-857
The other super cool scientist who won the 1989 Nobel Prize in Chemistry (besides Cech) was Sidney Altman. Whereas Cech get's brownie points for the awesome (possibly accidental) discovery he made, Altman gets points for an amazing experimental design. Altman and his lab team studied RNaseP, an enzyme with both RNA and protein components, which performs the reaction shown to the right: it cleaves the 5' end of rRNA, essentially activating the molecule (making it useable by the cell). They isolated the protein components (by RNA digestion by nucleases) and the RNA component (by digestion of protein by proteases) and then combined the different isolates with | the tRNA precursor molecule. They found that the protein by itself was inactive at physiological conditions, but they found that the RNA was only mostly inactive (there was some activity). Another experiment (in which excess RNAs were added to the enzyme, which would theoretically "clog up" the RNA component of RNaseP) confirmed that the enzyme's function was dependent on the RNA being available. In a third experiment, Altman tested the RNA component of the enzyme in different magnesium concentrations and was able to subject it to conditions in which it performed the reaction by itself. The reason that ribozymes are important, other than the fact that it is really cool that this molecule has catalytic properties in physiological conditions, is that ribozymes provide the empirical basis upon which theories on the origin of life can be made. Before these experiments, one big question scientists had dealt with was what came first: protein or RNA? These results allowed scientists to propose the RNA world hypothesis, which states that RNA molecules may have had an important catalytic role during the beginning of life, possibly assuming many of the roles that proteins have today. |
Check out Altman's 1983 paper in which he discusses one of the experiments that led to his discovery!
**Picture of RNase P from http://www.genesilico.pl/rnapathwaysdb/Pathway/reaction/77/
**Picture of RNase P pathway from http://www.umich.edu/~caflab/rnasep.htm