B_12-retro-Riboswitches:Constitutional Switching of B_12 Coenzymes Induced by Nucleotides

摘要

The recent discovery of "B_12-riboswitches" revealed a new mechanism of genetic control and established the biological relevance of the direct interaction between RNA and B_12 coenzymes.B_12-riboswitches are natural messenger RNAs(mRNAs)which bind coenzyme B_12(1)and then undergo a change in conformation("switch"),suggested to lead to inhibition of the expression of proteins relevant in B_12 biosynthesis or B_12 transport.Artificial RNA sequences with the ability to bind small molecules tightly,including vitamin B_12,have been prepared earlier by chemical in vitro evolution exoeriments.