EntE, EntS and TolC synergistically contributed to the pathogenesis of APEC strain E058.

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) shows an enhanced ability to cause infection outside the intestinal tract. Avian pathogenic E. coli (APEC), one type of ExPEC, causes avian colibacillosis, a disease of significant economic importance to poultry producers worldwide that is characterized by systemic infection. Some ExPEC strains as well as other pathogenic enterobacteria produce enterobactin, a catecholate siderophore used to sequester iron during infection. Here, we showed that disruption of enterobactin efflux via outer membrane protein TolC significantly decreased the pathogenicity of APEC strain E058. Furthermore, colonization and persistence assays performed using a chicken infection model showed that the ΔtolC mutant was obviously attenuated (p˂0.001). In contrast, disruption of enterobactin synthesis gene entE and/or the inner membrane transporter gene entS had little effect on pathogenicity. Analysis of growth kinetics revealed a significant reduction in the growth of triple mutant strain E058ΔentEΔentSΔtolC in iron-deficient medium compared with the wild-type strain (p˂0.001), while no growth impairment was noted for the E058ΔtolC mutant in either Luria-Bertani broth or iron-deficient medium. The E058ΔentEΔentSΔtolC mutant also showed significantly decreased virulence compared with single mutant strain E058ΔtolC. Low-copy complementation of strains E058ΔtolC and E058ΔentEΔentSΔtolC with plasmid-borne tolC restored virulence to wild-type levels in the chicken infection model. Macrophage infection assays showed that ingestion of E058ΔtolC by macrophage cell line HD11 cells was reduced compared with ingestion of the E058ΔentEΔentSΔtolC mutant. However, no significant differences were observed between the mutants and the wild-type in a chicken serum resistance assay. Together, these results suggest that EntE, EntS and TolC synergistically contributed to the pathogenesis of APEC strain E058 in an iron-deficient environment.

• Authors: Xiaohui Mu, Ruxia Gao, Wenhua Xiao, Qingqing Gao, Chunguang Cao, Huiqinq Xu, Song Gao, Xiufan Liu
• Journal: Microbial pathogenesis (Microb Pathog) Vol. 141 Pg. 103990 (Apr 2020) ISSN: 1096-1208 [Electronic] England
• PMID: 31978427 (Publication Type: Journal Article)
• Copyright: Copyright © 2020 Elsevier Ltd. All rights reserved.

Chemical References

• Bacterial Outer Membrane Proteins
• Escherichia coli Proteins
• Membrane Transport Proteins
• Siderophores
• Virulence Factors
• tolC protein, E coli
• Enterobactin
• Ligases
• 2,3-dihydroxybenzoate-AMP ligase, E coli

Topics

• Animals
• Bacterial Outer Membrane Proteins (genetics)
• Birds
• Cell Line
• Chickens (microbiology)
• Enterobactin (metabolism)
• Escherichia coli (genetics, growth & development, pathogenicity)
• Escherichia coli Infections
• Escherichia coli Proteins (genetics)
• Ligases (genetics)
• Macrophages
• Membrane Transport Proteins (genetics)
• Mutation
• Poultry Diseases (microbiology)
• Siderophores (metabolism)
• Virulence Factors (genetics)