An in silico structural and physicochemical characterization of TonB-dependent copper receptor in A. baumannii.

Acinetobacter baumannii is an opportunistic multidrug resistant pathogen. TonB-dependent copper receptor is an outer membrane protein and has a role in binding of A. baumannii to host cell via attachment to fibronectin. Moreover, it is highly expressed in biofilm community. In this study the properties of copper receptor were analyzed in silico and its vaccine potential was investigated. TonB-dependent copper and iron receptor domains plus one plug domain at N-terminal were determined by domain analysis. Topology modeling showed 22 β-strands, 11 loops and 10 periplasmic turns. Interaction of this protein with TonB2 energy transducer was also indicated. Beside the antigenicity, this protein could take part in bacterial virulence. The more preferable 3D structure was selected amongst all 26 predicted structures, refined and used in prediction of ligand binding site and conformational epitope. The results of B and T-cell epitope mapping indicated 8 potential areas in the protein sequence and structure that seems to be able to stimulate both humoral and cellular immune responses. Based on the alignment result, this protein and all selected epitopes are extremely conserved among A. baumannii strains which can be tested as sub unit vaccine by in vivo studies.