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Vet Res. 2018 Feb 26;49(1):23. doi: 10.1186/s13567-018-0519-9.

Binding determinants in the interplay between porcine aminopeptidase N and enterotoxigenic Escherichia coli F4 fimbriae.

Xia P1,2,3, Quan G1,2,3, Yang Y1,2,3, Zhao J1,2,3, Wang Y1,2, Zhou M1,2, Hardwidge PR4, Zhu J1,2, Liu S5, Zhu G6,7,8.

Author information

1
College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China.
2
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
3
Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225009, China.
4
College of Veterinary Medicine, Kansas State University, Manhattan, KS, 66506, USA.
5
National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, China.
6
College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China. yzgqzhu@yzu.edu.cn.
7
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China. yzgqzhu@yzu.edu.cn.
8
Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225009, China. yzgqzhu@yzu.edu.cn.

Abstract

The binding of F4+ enterotoxigenic Escherichia coli (ETEC) and the specific receptor on porcine intestinal epithelial cells is the initial step in F4+ ETEC infection. Porcine aminopeptidase N (APN) is a newly discovered receptor for F4 fimbriae that binds directly to FaeG adhesin, which is the major subunit of the F4 fimbriae variants F4ab, F4ac, and F4ad. We used overlapping peptide assays to map the APN-FaeG binding sites, which has facilitated in the identifying the APN-binding amino acids that are located in the same region of FaeG variants, thereby limiting the major binding regions of APN to 13 peptides. To determine the core sequence motif, a panel of FaeG peptides with point mutations and FaeG mutants were constructed. Pull-down and binding reactivity assays using piglet intestines determined that the amino acids G159 of F4ab, N209 and L212 of F4ac, and A200 of F4ad were the critical residues for APN binding of FaeG. We further show using ELISA and confocal microscopy assay that amino acids 553-568, and 652-670 of the APN comprise the linear epitope for FaeG binding in all three F4 fimbriae variants.

PMID:
29482635
PMCID:
PMC5828407
DOI:
10.1186/s13567-018-0519-9
[Indexed for MEDLINE]
Free PMC Article

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