The structure of the RlmB 23S rRNA methyltransferase reveals a new methyltransferase fold with a unique knot.
In Escherichia coli, RlmB catalyzes the methylation of guanosine 2251, a modification conserved in the peptidyltransferase domain of 23S rRNA. The crystal structure of this 2'O-methyltransferase has been determined at 2.5 A resolution. RlmB consists of an N-terminal domain connected by a flexible extended linker to a catalytic C-terminal domain and forms a dimer in solution. The C-terminal domain displays a divergent methyltransferase fold with a unique knotted region, and lacks the classic AdoMet binding site features. The N-terminal domain is similar to ribosomal proteins L7 and L30, suggesting a role in 23S rRNA recognition. The conserved residues in this novel family of 2'O-methyltransferases cluster in the knotted region, suggesting the location of the catalytic and AdoMet binding sites.
Michel
Gurvan
G
Biotechnology Research Institute, National Research Council of Canada and Montreal Joint Centre for Structural Biology, Montreal, Quebec, Canada.
Sauvé
Véronique
V
Larocque
Robert
R
Li
Yunge
Y
Matte
Allan
A
Cygler
Miroslaw
M
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D008780:Methyltransferases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D012338:RNA, Ribosomal, 23S / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D012338:RNA, Ribosomal, 23S; D008780:Methyltransferases; C035181:rRNA (adenosine-O-2'-)methyltransferase