SAM riboswitch (S-box leader)

The SAM riboswitch (also known as the S-box leader and the SAM-I riboswitch) is found upstream of a number of genes which code for proteins involved in methionine or cysteine biosynthesis in Gram-positive bacteria. Two SAM riboswitches in Bacillus subtilis that were experimentally studied act at the level of transcription termination control.