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ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. Veterinary Infectious Diseases
Volume 11 - 2024 |
doi: 10.3389/fvets.2024.1410113
This article is part of the Research Topic One Health Approach in Addressing Microbial Food-Safety Challenges View all 5 articles
Protamine cleavage specificity of the avian pathogen Escherichia coli OmpT reveals two substrate-binding sites related to virulence
Provisionally accepted- Yangzhou University, Yangzhou, China
The pathogenic nature of bacteria can be increased by cleaving antimicrobial peptides using omptins, to avoid or counter the host's natural immune defenses. Plasmid-encoded OmpT (pOmpT or ArlC) in avian pathogenic Escherichia coli (APEC), like the chromosome-encoded OmpT (cOmpT), belongs to the omptin family and both exhibit highly similar sequences and structures. Through sequence alignment and physiological examinations, pOmpT has been identified as a virulence factor, distinct from cOmpT in terms of substrate specificity. When pOmpT is compared with cOmpT regarding their proteolytic activities and target substrates, Asp 267 and Ser 276 on loop 5 of cOmpT are found to be binding sites that facilitate substrate anchoring and enhance substrate cleavage (protamine or synthetic peptide) by the catalytic center. Conversely, the characteristics of residues at positions 267 and 276 on loop 5 of pOmpT inhibit protamine cleavage, yet allow the specific cleavage of the human antimicrobial peptide RNase 7, which plays a role in host defense. This finding suggests a relationship between these two binding sites and substrate specificity. Furthermore, the substratebinding sites (residues 267 and 276, particularly residue 267) of cOmpT and pOmpT are determined to be critical in the virulence of APEC. In summary, residues 267 and 276 of pOmpT are crucial for the pathogenicity of APEC and offer new insights into the determinants of APEC virulence and the development of antimicrobial drugs.
Keywords: Avian Pathogenic Escherichia coli, proteolytic activity, Cleavage specificity, Substrate affinity, Substrate-binding site, Virulence
Received: 31 Mar 2024; Accepted: 26 Aug 2024.
Copyright: © 2024 Liu, Jiang, Wang, Wu, Gao, Huan and Gao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Song Gao, Yangzhou University, Yangzhou, China
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