Crystal Structure and Functional Analysis of the SARS-Coronavirus RNA Cap 2′-O-Methyltransferase nsp10/nsp16 Complex
Figure 5
Stick model of RNA bound to the nsp16 RNA binding groove and Sinefungin in the methyltransferase active site.
A) In this representation, Sinefungin was preferred over SAH because one of its NH2 groups approximates the direction of a transferred CH3 group from the SAM substrate. Carbon is white, oxygen is red, nitrogen is blue and phosphorous is orange. Nsp16 and nsp10 are rendered as a solvent-accessible surface colored grey and wheat respectively. The Sinefungin molecule defines the methyltransferase active site. Missing residues in the 135-137 loop (see text) are indicated by a shaded blue dotted box. Position of Y30 and Y132 are indicated. Y30 generated poor electron density (see « Methods ») and its aromatic ring position has been manually adjusted before generation of this image. B) Close caption of the methyltransferase active site showing distance between the NH2 of Sinefungin to the 2′-O of the ribose of the first base, thus mimicking the position of the methyl of the S-adenosylmethionine.