tRNA-modifying MiaE protein from Salmonella typhimurium is a nonheme diiron monooxygenase

Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13295-300. doi: 10.1073/pnas.0704338104. Epub 2007 Aug 6.


MiaE catalyzes the posttranscriptional allylic hydroxylation of 2-methylthio-N-6-isopentenyl adenosine in tRNAs. The Salmonella typhimurium enzyme was heterologously expressed in Escherichia coli. The purified enzyme is a monomer with two iron atoms and displays activity in in vitro assays. The type and properties of the iron center were investigated by using a combination of UV-visible absorption, EPR, HYSCORE, and Mössbauer spectroscopies which demonstrated that the MiaE enzyme contains a nonheme dinuclear iron cluster, similar to that found in the hydroxylase component of methane monooxygenase. This is the first example of an enzyme from this important class of diiron monooxygenases to be involved in the hydroxylation of a biological macromolecule and the second example of a redox metalloenzyme participating in tRNA modification.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Escherichia coli / genetics
  • Mixed Function Oxygenases / metabolism*
  • Molecular Sequence Data
  • RNA, Transfer / metabolism*
  • Salmonella typhimurium / metabolism*
  • Sequence Homology, Amino Acid
  • Spectrophotometry, Ultraviolet
  • Transformation, Genetic


  • Bacterial Proteins
  • RNA, Transfer
  • Mixed Function Oxygenases