Figure 1

PPI Fingerprint concept. (A) The idealized sequence space of fructose bisphosphate aldolase represented as a phylogenetic tree rooted on a specific sequence. In this family of proteins, we observe either dimeric (blue) or tetrameric quaternary structures (green). The red concentric circles represent the sequence identity thresholds used to calculate the interface conservation score (C_score). (B) The PPI fingerprint curves of several homologs with dimeric (blue) or tetrameric (green) quaternary structures (standard error is used for the error area). The MSA is obtained running HHblits⁴² against the non-redundant (20% sequence identity) NCBI database with a threshold of 70% as minimum coverage. Considering the complete MSA (below 20% sequence identity threshold) the support for a conserved interface is stronger for dimers, while with more stringent threshold (50–60%) the tetrameric option has a stronger conservation signal.