THE SELF-CLEAVAGE OF LARIAT-RNA

Lariat-RNAs 3 and 4 undergo site-specific self-cleavage reaction at th e G3 --> C6/U7 phosphodiester bond by the nucleophilic attack of 2'-OH of G3 sugar moiety to its 3-phosphate to give 5'hydroxyl terminal at C6 or U7 and 2, 3-cyclic phosphodiester of G3 whereas lariat-tetramer 1, pentamer 2, the cyclic-A(2' --> 5)G-tetramer 5 and the cyclic-A(3' --> 5')G-tetramer 6 are completely stable. The lariat-RNAs 3 and 4 are the smallest RNA known to undergo self-cleavage which is reminiscent of the RNA-hammerhead (Ribozyme) activity. The geometry of the cleavag e-site in 3 and 4 has been defined by full conformational analysis by NMR and molecular dynamics calculation in water.