RNA-catalyzed RNA polymerization: Accurate and general RNA-templated primer extension

The RNA world hypothesis regarding the early evolution of Life relies on th e premise that some RNA sequences can catalyze RNA replication. In support of this conjecture, we describe here an RNA molecule that catalyzes the typ e of polymerization needed for RNA replication. The ribozyme uses nucleosid e triphosphates and the coding information of an RNA template to extend an RNA primer by the successive addition of up to 14 nucleotides-more than a c omplete turn of an RNA helix. Its polymerization activity is general in ter ms of the sequence and the Length of the primer and template RNAs, provided that the 3' terminus of the primer pairs with the template. Its polymeriza tion is also quite accurate: when primers extended by 11 nucleotides were c loned and sequenced, 1088 of 1100 sequenced nucleotides matched the templat e.