RNA World Hypothesis - Implications of The RNA World

Implications of The RNA World

The RNA world hypothesis, if true, has important implications for the definition of life. For most of the time that followed Watson and Crick's elucidation of DNA structure in 1953, life was largely defined in terms of DNA and proteins: DNA and proteins seemed the dominant macromolecules in the living cell, with RNA only aiding in creating proteins from the DNA blueprint.

The RNA world hypothesis places RNA at center-stage when life originated. This has been accompanied by many studies in the last ten years that demonstrate important aspects of RNA function not previously known—and supports the idea of a critical role for RNA in the mechanisms of life. In 2001, the RNA world hypothesis received a boost with the deciphering of the 3-dimensional structure of the ribosome—which revealed that the key catalytic sites of ribosomes are composed of RNA, and that proteins hold no major structural role and are of peripheral functional importance. Specifically, peptide bond formation, the reaction that binds amino acids together into proteins, is now known to be catalyzed by an adenine residue in the rRNA: the ribosome is a ribozyme. This finding suggests that RNA molecules were most likely capable of generating the first proteins.

Other interesting discoveries demonstrate a role for RNA beyond a simple message or transfer molecule. These include the importance of small nuclear ribonucleoproteins (snRNPs) in the processing of pre-mRNA and RNA editing, and reverse transcription from RNA in Eukaryotes in the maintenance of telomeres in the telomerase reaction.