The riboswitch-mediated control of sulfur metabolism in bacteria

Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5052-6. doi: 10.1073/pnas.0531307100. Epub 2003 Apr 17.


Many operons in Gram-positive bacteria that are involved in methionine (Met) and cysteine (Cys) biosynthesis possess an evolutionarily conserved regulatory leader sequence (S-box) that positively controls these genes in response to methionine starvation. Here, we demonstrate that a feed-back regulation mechanism utilizes S-adenosyl-methionine as an effector. S-adenosyl-methionine directly and specifically binds to the nascent S-box RNA, causing an intrinsic terminator to form and interrupt transcription prematurely. The S-box leader RNA thus expands the family of newly discovered riboswitches, i.e., natural regulatory RNA aptamers that seem to sense small molecules ranging from amino acid derivatives to vitamins.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Gram-Positive Bacteria / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Operon
  • RNA, Bacterial / metabolism
  • Sulfur / metabolism*
  • Terminator Regions, Genetic
  • Transcription, Genetic


  • RNA, Bacterial
  • Sulfur