PROSITE documentation PDOC00871
Ribosomal RNA adenine dimethylases signature


A number of enzymes responsible for the dimethylation of adenosines in ribosomal RNAs (EC have been found [1,2] to be evolutionary related. These enzymes are:

  • Bacterial 16S rRNA dimethylase (gene ksgA), which acts in the biogenesis of ribosomes by catalyzing the dimethylation of two adjacent adenosines in the loop of a conserved hairpin near the 3'-end of 16S rRNA. Inactivation of ksgA leads to resistance to the aminoglycoside antibiotic kasugamycin.
  • Yeast 18S rRNA dimethylase (gene DIM1), which is functionally similar to ksgA and that dimethylates twin adenosines in the 3'-end of 18S rRNA.
  • Bacterial 'erm' methylases. These enzymes confer resistance to macrolide- lincosamide-streptogramin B (MLS) antibiotics - such as erythromycin - by dimethylating the adenine residue at position 2058 of 23S rRNA thus resulting in a reduced affinity between ribosomes and the MLS antibiotics.
  • Caenorhabditis elegans hypothetical protein EO2H1.1.

The best conserved region in these enzymes is located in the N-terminal section and corresponds to a region that is probably involved in S-adenosyl methionine (SAM) binding.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

RRNA_A_DIMETH, PS01131; Ribosomal RNA adenine dimethylases signature  (PATTERN)


1Authorsvan Gemen B. van Knippenberg P.H.
Source(In) Nucleic acid methylation, Clawson G.A., Willis D.B., Weissbach A., Jones P.A., Eds., pp.19-36, Alan R. Liss Inc, New-York, (1990).

2AuthorsLafontaine D. Delcour J. Glasser A.L. Desgres J. Vandenhaute J.
TitleThe DIM1 gene responsible for the conserved m6(2)Am6(2)A dimethylation in the 3'-terminal loop of 18 S rRNA is essential in yeast.
SourceJ. Mol. Biol. 241:492-497(1994).
PubMed ID8064863

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