Computational analyses of bifurcated inter-protein interactions in
protein-protein assemblies reveal their pivotal role in conferring
stability
Abstract
Majority of the proteome is constituted by oligomers and their function
is governed by underlying protein-protein interactions. Interfacial
residues, namely residues right at the interface of two protein chains,
are known to confer stability and specificity in dimers. However, other
interactions play a significant role in the formation and maintenance of
oligomers in protein assemblies as well. Inter-protein bifurcated
interactions are those where one residue simultaneously interacts with
two residues belonging to two neighbouring protein chains. The
characteristic features for such higher order interactions remain
largely unexplored and unknown. In this study, we focused on r esidues
specifically involved in b ifurcated i nteractions (referred as
RBI). We examine the bifurcated inter-protein interactions by assembling
a dataset of protein assemblies of known 3D structures. We have
characterized the type of interactions and the residues involved in the
interactions using parameters like energy contributions and conservation
score. We find that the residues participating in bifurcated
inter-protein interactions contribute more to the stability of the
complex than other interfacial residues. Furthermore, we have presented
examples where mutation of a residue involved in a bifurcated
interaction results in detrimental outcomes. This study highlights the
significance of inter-protein bifurcated interactions that contribute to
the stability of multiple interfaces in protein oligomers and hence
contribute to the expansion of the understanding of protein assemblies.