Cobalamin riboswitch

Cobalamin riboswitch also known as B12-element is a cis-regulatory element which is widely distributed in 5' untranslated regions of vitamin B12 (Colbalamin) related genes in bacteria. Riboswitches are metabolite binding domains within certain messenger RNAs (mRNAs) that serve as precision sensors for their corresponding targets. Allosteric rearrangement of mRNA structure is mediated by ligand binding, and this results in modulation of gene expression. Cobalamin in the form of adenosylcobalamin (Ado-CBL) is known to repress expression of genes for vitamin B12 biosynthesis and be transported by a post-transcriptional regulatory mechanism, which involves direct binding of Ado-CBL to 5' UTRs.