SMK box riboswitch
RNA family
From Wikipedia, the free encyclopedia
The SMKbox riboswitch (also known as SAM-III) is an RNA element that regulates gene expression in bacteria.[2][3] The SMK 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.
| SMK box translational riboswitch | |
|---|---|
A representation of the SMK box translational riboswitch secondary structure including a colour scheme that indicates the degree of sequence conservation. | |
| Identifiers | |
| Symbol | SMK_box_riboswitch |
| Alt. Symbols | SAM-III, SMK |
| Rfam | RF01767 |
| Other data | |
| RNA type | Riboswitch |
| Domain | Bacillota |
| PDB structures | PDBe 3e5f 3e5e 3e5c |
There are other known SAM-binding riboswitches such as SAM-I and SAM-II, but these appear to share no similarity in sequence or structure to SAM-III.
Structure
The crystal structure of the riboswitch from E. faecalis was solved by X-ray crystallography. The structure showed that the most conserved nucleotides involved in SAM binding were organised around a junction between three helices.[1] In some species there are large insertions of up to 210 nucleotides within this structure.
