Different activated methyl cycle pathways affect the pathogenicity of avian pathogenic Escherichia coli

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Updated: Feb 19, 2026

Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing
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Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing

Published on: December 23, 2022

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Da Xu1, Jiakun Zuo2, Zhaoguo Chen2

  • 1Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, PR China.

Veterinary Microbiology
|November 6, 2017
PubMed

Insights

The activated methyl cycle (AMC) impacts bacterial pathogenicity. Disrupting the LuxS/Pfs pathway significantly reduces avian pathogenic E. coli (APEC) virulence, while introducing the SahH pathway offers partial protection.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • The activated methyl cycle (AMC) regulates S-adenosyl-l-homocysteine (SAH) levels, crucial for bacterial pathogenicity.
  • Two primary AMC pathways exist in bacteria: the LuxS/Pfs pathway producing autoinducer-2 (AI-2) and the SahH pathway that does not.

Purpose of the Study:

  • To investigate the impact of different AMC pathways on the pathogenicity of avian pathogenic Escherichia coli (APEC).
  • To compare the virulence of APEC strains with distinct AMC pathway compositions.

Main Methods:

  • Engineered APEC strains by transforming the sahH gene into wild-type and pfs mutant strains.
  • Assessed bacterial growth rate, AI-2 activity, motility, adherence, invasion, and survival in vivo.
  • Determined the 50% lethal dose (LD50) in ducklings.

Main Results:

  • Different AMC pathways influenced APEC growth rate, AI-2 activity, and motility.
  • The DE17Δpfs strain (lacking LuxS/Pfs) showed a 650-fold reduction in LD50 compared to the wild-type DE17 strain.
  • The SahH-DE17Δpfs strain (SahH pathway only) had a 52-fold reduction in LD50, with significantly reduced adherence, invasion, and in vivo survival.

Conclusions:

  • The LuxS/Pfs pathway is critical for APEC virulence.
  • The SahH pathway can partially restore virulence in the absence of the LuxS/Pfs pathway.
  • Modulating AMC pathways represents a potential strategy for controlling APEC infections.
Keywords:
Activated methyl cycleAvian pathogenic Escherichia coliPathogenicityQuorum sensingS-adenosyl-l-homocysteine hydrolase

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