Additional file 1:

Supplementary tables. Table S1: Summary of interface cluster analysis of the proteins considered in our dataset at I_min = 6%. Table S2: RMSD values (backbone rmsd) of LuxS protein from 23 organisms in our dataset. Table S3: Detailed description of residues present in the interface clusters at I_min = 6% for Class (I–VI). Table S4: Description of the hubs present in LuxS from extremophiles at different I_min values (the numbering of residues are done according to sequence). Table S5: Various bacterial species and the mini-triad motif associated with them across our dataset. Table S1: The total number of interface clusters vary from 4–12 and the total number of residues in the interface clusters vary from 36 to 73. The mini-triad pattern for each protein is also given in the table with the physiological manifestations of LuxS mutation in each class (except III, IV and V) except for T. thermophilus (class IV) in which the mini-triad pattern is absent from the sequence. Table S2: It can be readily noted that all the rmsd values are < 1.5, indicating the similarity in the backbone structures for the proteins in our dataset. Bold highlights indicate the rmsd values within members of a particular class. Table S3: Some clusters have been merged together for simplicity of representation. Table S4: The table reveals the presence of hubs at higher I_min values for class IV; for m1psy (psychrophile), 1inn and m1geo (extreme radiation-resistent) and m1the (hyperthermophile). They all belong to the broad category of extremophiles. Table S5: Various bacterial species and the mini-triad motif associated with them across our dataset. The absolute mini-triad motifs are indicated without 'X'. Here GKD essentially means GXKXD.

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Additional file 2:

Figure S1(a-b). Figure S1: All interface amino acid clusters for the members of (a) class II and (b) class III are plotted on the superposed backbones of the four LuxS structures within class II and III respectively. The residues are represented as van der Waal's spheres and the backbones are given in transparent new cartoon. The figures show an overall uniform topological orientation of all the interface clusters for members within a class; the class III interface clusters lack the mini-triad and the connecting bridge between the two subunits in the lower half of the protein in contrast to that shown in class II. So they share a distinct overall distribution as becomes evident from the figure.

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Additional file 3:

Figure S2: Frequency of occurrence of various bacterial species in our dataset consisting of 202 LuxS proteins. The abbreviations used for bacterial species are a part of the UNIPROT id; e.g. LUXS_BACSU means LuxS from Bacillus (species) subtilis (organism). We have indicated the species by three letter codes e.g. BAC in Figure S2.

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