In silico mutation of aromatic with aliphatic amino acid residues in Clostridium perfringens epsilon toxin (ETX) reduces its binding efficiency to Caprine Myelin and lymphocyte (MAL) protein receptors

Abstract

Enterotoxaemia (ET) is a severe disease that affects domestic ruminants, including sheep and goats, and is caused by Clostridium perfringens type B and D strains. The disease is characterized by the production of Epsilon toxin (ETX), which has a significant impact on the farming industry due to its high lethality. The binding of ETX to the host cell receptor is crucial, but still poorly understood. Therefore, the structural features of goat Myelin and lymphocytic (MAL) protein were investigated and defined in this study. We induced the mutations in aromatic amino acid residues of ETX and substituted them with aliphatic residues at domains I and II. Subsequently, protein-protein interactions (PPI) were performed between ETX (wild)-MAL and ETX (mutated)-MAL protein predicting the domain sites of ETX structure. Further, molecular dynamics (MD) simulation studies were performed for both complexes to investigate the dynamic behavior of the proteins. The binding efficiency between ‘ETX (wild)-MAL protein’ and ‘ETX (mutated)-MAL protein complex’ interactions were compared and showed that the former had stronger interactions and binding efficiency due to the higher stability of the complex. The MD analysis showed destabilization and higher fluctuations in the PPI of the mutated heterodimeric ETX-MAL complex which is otherwise essential for its functional conformation. Such kind of interactions with mutated functional domains of ligands provided much-needed clarity in understanding the pre-pore complex formation of epsilon toxin with the MAL protein receptor of goats. The findings from this study would provide an impetus for designing a novel vaccine for Enterotoxaemia in goats.

Communicated by Ramaswamy H. Sarma

Keywords:

• Epsilon toxin (ETX)
• enterotoxaemia (ET)
• MAL protein
• protein-protein interactions
• molecular dynamics

Data availability statement

The data supporting the conclusion of this study are available from the corresponding author.

Authors’ contributions

SK and KG contributed to conception and design of the research. SKB, SK and SM performed the experiments. SK, SKB and KG drafted the manuscript. SK, KG, SKB, ACS, RP, UBA, RSP and AR did review and editing. All authors contributed to manuscript revision, read and approved the submitted version.

Disclosure statement

The authors have no conflicts of interest to declare.

Additional information

Funding

This work was supported by Indian Council of Agricultural Research, Ministry of Agriculture and 743 Farmers’ Welfare Govt. of India, CABIN grant (F. no. Agril. Edn.4-1/2013-A&P). The funding organization has not played any role in the study design or the preparation of the manuscript.