Residues in PvPGIP2 Residue No. Residues in FmPG Residue No. Residues in GmPGIP3 Residue No. Residues in FmPG Residue No. 152 178 224 271 167 188 189 243 245 152 178 224 225 271 167 188 189 243 245 V S Q H D D D R K V S Q K H D D D R K Change in SASA (in nm2) upon complexation of GmPGIP3 with FmPG 0.726572 0.264561 0.496097 1.01276 0.348913 0.381939 0.150885 0.158454 0.403263 0.396312 0.4249 0.517371 0.6919 1.21099 0.348913 0.381939 0.150885 0.158454 0.403263 0.363286 0.11834 0.137248 0.585858 0.306561 0.141431 0.0896238 0.0127235 0.510823 0.066052 0.182517 0.29529 0.1325 0.712258 0.292443 0.207483 0.033026 0.0254469 0.523546 Residue name SASA in PvPGIP2 SASA in complex Residue name SASA in PvPGIP2 SASA in complex Residue name SASA in GmPGIP3 SASA in complex Residue name SASA in GmPGIP3 SASA in complex BMC Genomics 2009, 10(Suppl 3):S19 http://www.biomedcentral.com/1471-2164/10/S3/S19 Table 1: Change in Solvent Accessible Surface Area (SASA) in PGIP and PG upon complexation: The table summarizes the change in solvent accessible surface area of some biologically important residues of PvPGIP2-FmPG and GmPGIP3-FmPG before and after complexation Change in SASA (in nm2) upon complexation of PvPGIP2 with FmPG the face similar to the one in PvPGIP2 (Figure 4B) of the PvPGIP2-FmPG complex, is considered for further studies to confirm the inability of the protein in inhibition towards the enzyme. Docking studies of FmPG-GmPGIP3 It has been reported that GmPGIP3 possesses an inhibiting activity towards the PG of Fusarium monili- forme like PvPGIP2. No mutational studies being available for GmPGIP3, the docked structure of the GmPGIP3-FmPG complex was therefore selected from the top scoring ten models reported by GRAMM-X using the knowledge obtained from experimental studies carried out for PvPGIP2. In the selected model of the complex (Figure 4C), GmPGIP3 has blocked the active site cleft of FmPG. The docked model therefore is in agreement with the experimental observation of the ability of GmPGIP3 in inhibiting the enzymatic activity of FmPG. The important residues V(152), S(178), Q (224) and H(271) of GmPGIP3 that are also present in PvPGIP2 show considerable decrease in solvent acces- sible surface area (Table 1) indicating their active involvement in protein-protein interaction, an identical observation that holds true for PvPGIP2. Thus like PvPGIP2, GmPGIP3 too blocks the active site cleft and hinders the substrate binding site of FmPG bearing a similar mode of competitive inhibition. Comparative study of protein-protein interactions in the three complexes Ionic interactions We have used PIC [28] for comparison of interactions recognized in the three complexes. Ionic interaction that is believed to play an important role in protein-protein Page 7 of 12 (page number not for citation purposes)