Figure 7
Panel A and B: ribbon diagrams of GNA maize (A) and GNA (B) highlighting the mannose-binding sites I, II and III in both structures. Panel C: electronegative cavity (white dotted line) in the region of site I of GNAmaize (open white circle in Panel A) containing residues Ser24, Glu26, Ala26, Tyr38, Asn40 and Asn41 that could be involved in the binding of monosaccharides. Electronegative and electropositive potentials are colored red and blue, respectively. Neutral regions are colored white. Panel D,G,J and M: topography of site II of GNAmaize (D) and GNA (G) and site III of GNAmaize (J) and GNA (M) showing the anchoring of MeMan into the mannose-binding cavity. The yellow star indicates the protruding His78 residue that creates a steric clash with O6 of MeMan (D). The overall topography of the mannose-binding sites is indicated by red dotted lines. Panel E,H,K and N: ribbon diagrams showing the anchoring of MeMan into mannose-binding site II of GNAmaize (E) and GNA (H) and site III of GNAmaize (K) and GNA (N). Residues interacting with MeMan are in stick representation and are labelled. Panel F,I,L and O: stick representation of residues interacting with MeMan in site II of GNAmaize (F) and GNA (I) and site III of GNAmaize (L) and GNA (O). Hydrogen bonds are represented by deep blue dotted lines. Note the steric clash occurring between His78 and O6 of MeMan in site II of GNAmaize (F).