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Generation of In-Frame Gene Deletion Mutants in Pseudomonas aeruginosa and Testing for Virulence Attenuation in a Simple Mouse Model of Infection
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Generation of In-Frame Gene Deletion Mutants in Pseudomonas aeruginosa and Testing for Virulence Attenuation in a Simple Mouse Model of Infection

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ampG gene of Pseudomonas aeruginosa and its role in β-lactamase expression

Ying Zhang1, Qiyu Bao, Luc A Gagnon

  • 1Molecular Genetics and Microbiology, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610-0266, USA.

Antimicrobial Agents and Chemotherapy
|August 18, 2010
PubMed

Insights

Pseudomonas aeruginosa AmpG transporter is crucial for beta-lactam resistance. Inhibiting AmpG increases susceptibility to beta-lactams, offering a potential strategy to combat infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • The ampG gene in enterobacteria encodes a permease essential for transporting specific molecules involved in ampC beta-lactamase induction and cell wall recycling.
  • Pseudomonas aeruginosa possesses two AmpG homologues, AmpG (PA4393) and AmpGh1 (PA4218), with varying sequence identities to E. coli AmpG.

Purpose of the Study:

  • To investigate the functional roles of the two AmpG homologues in Pseudomonas aeruginosa, specifically their contribution to beta-lactam resistance.
  • To explore the potential of inhibiting AmpG activity as a strategy to enhance beta-lactam efficacy against P. aeruginosa.

Main Methods:

  • Gene inactivation (deletion) of ampG and ampGh1 in P. aeruginosa strains.
  • Complementation studies using cloned ampG and ampGh1 genes.
  • Assessment of beta-lactam resistance levels in wild-type and mutant strains.
  • Inhibition of AmpG function using carbonyl cyanide m-chlorophenylhydrazone (CCCP).

Main Results:

  • Inactivation of ampG significantly repressed intrinsic beta-lactam resistance in P. aeruginosa, while ampGh1 deletion had minimal impact.
  • Deletion of ampG in an ampD-null mutant abolished high-level beta-lactam resistance.
  • Only the cloned ampG gene (PA4393) could complement both P. aeruginosa and E. coli ampG mutants, indicating it encodes the functional AmpG.
  • CCCP effectively inhibited AmpG function, leading to increased beta-lactam sensitivity in both laboratory and clinical P. aeruginosa isolates.

Conclusions:

  • PA4393 represents the functional AmpG protein in P. aeruginosa, playing a critical role in beta-lactam resistance.
  • Inhibition of AmpG activity presents a promising therapeutic strategy to overcome beta-lactam resistance in P. aeruginosa, particularly in AmpC-hyperproducing strains.

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