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Figure 2.
Figure 2. The RNA-binding surface on the Vts1 SAM domain.
(a) Weighted-averaged18 amide 1H and 15N chemical shift changes
upon SRE RNA binding where d[av](HN)=[dH2+(dN/5)2)/2]1/2. Bars
are colored according to the magnitude of the chemical shift
change (red, >0.3 ppm; yellow, >0.1 ppm). (b) Chemical shift
changes, sequence conservation, and electrostatic charge are
mapped onto the surface of the free X-ray structure of Vts1 SAM
domain. HSQC perturbations are colored according to (a). The
linewidth of Lys467 sharpens significantly upon RNA binding and
is colored orange. Sequence identity (in purple) and sequence
similarity (in pink) among Vts1 homologs coincides with the SRE
binding surface deduced from chemical shift perturbations. The
RNA-binding site demonstrates basic charge distribution (red;
negative potential; blue, positive potential). Molecular
structure representations and electrostatic calculations were
made with pyMOL (http://pymol.sourceforge.net).
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