SMK box riboswitch

The S_MK box riboswitch is an RNA element that regulates gene expression in bacteria.cite journal |author=Fuchs RT, Grundy FJ, Henkin TM |title=The S(MK) box is a new SAM-binding RNA for translational regulation of SAM synthetase |journal=Nat. Struct. Mol. Biol. |volume=13 |issue=3 |pages=226–33 |year=2006 |pmid=16491091 |doi=10.1038/nsmb1059] cite journal |author=Fuchs RT, Grundy FJ, Henkin TM |title=S-adenosylmethionine directly inhibits binding of 30S ribosomal subunits to the SMK box translational riboswitch RNA |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=104 |issue=12 |pages=4876–80 |year=2007 |pmid=17360376 |doi=10.1073/pnas.0609956104] The S_MK box riboswitch is found in the 5' UTR of the MetK gene in lactic acid bacteria. The structure of this element changes upon binding to S-adenosyl methionine (SAM) to a conformation that blocks the shine-dalgarno sequence and blocks translation of the gene.

There are two other known SAM-binding riboswitches: SAM-I, SAM-II, but these appear to share no similarity in sequence or structure.

tructure

This riboswitch is composed of a single stem-loop. In some species there are large insertions of up to 210 nucleotides within this structure.

References