Molecular docking of bacteriocin enterocin P peptide with mastitis-causing E. coli antigen in cattle

Excessive use of antibiotics to treat diseases such as mastitis in dairy cows caused by Escherichia coli has led to the emergence of antibiotic-resistant bacteria, which is considered a threat to public health. Nowadays, antimicrobial peptides such as bacteriocins have attracted more attention as potential antimicrobial agents. Therefore, the study of their stability and antibacterial activity in physiological conditions is very important. In order to investigate the thermal stability of Enterocin P peptide (EntP), the third structure of EntP was first predicted using the I-TASSER server. Then, the stability of this structure was evaluated by dynamic conditions for this purpose, the simulation was performed using GROMACS software in 400 ns at cow body temperature (312 °K). Finally, the root-mean-square deviation (RMSD) graph of this peptide was plotted against time along the simulation trajectory. ClusPro online server was used to study the interaction of peptide with LptD surface protein from Escherichia coli bacterium causing mastitis. In the in vitro phase of this study, the minimum inhibitory concentration (MIC) and minimum dissociation concentration (MBC) of EntP peptide were estimated based on the microbroth method on Escherichia coli. The results showed that the best predicted structure of EntP peptide by I-TASSER server had a C-score of 1.4 which was selected. The values reported by the ERRAT and Verify3D plots indicated that the tertiary structure predicted for the EntP peptide was satisfactory. The RMSD graph related to the thermal stability of EntP at bovine body temperature showed that the structure of EntP peptide is stable after 400 ns of the simulation trajectory. The results of molecular docking also showed that this peptide was correctly attached to the LptD antigen. After measuring the MIC, the bacteria were cultured and the MBC was obtained, which were estimated at 48.25 and 96.5 μg/ml, respectively. This peptide could be used as an alternative to antibiotics or in combination with them for the treatment of infections with the origin of Escherichia coli.