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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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Mutation of the gene encoding monothiol glutaredoxin (GrxD) in Pseudomonas aeruginosa increases its susceptibility to

Adisak Romsang1, Panithi Leesukon2, Jintana Duangnkern1

  • 1Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand.

International Journal of Antimicrobial Agents
|January 17, 2015
PubMed

Insights

A Pseudomonas aeruginosa mutant lacking the GrxD enzyme showed increased susceptibility to polymyxin B. Targeting GrxD could enhance polymyxin effectiveness against drug-resistant infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Drug Discovery

Background:

  • Pseudomonas aeruginosa causes severe hospital-acquired infections with high mortality due to drug resistance.
  • Polymyxins are last-line antibiotics for treating multidrug-resistant (MDR) P. aeruginosa.
  • Monothiol glutaredoxin (GrxD) is involved in reducing disulphide bonds in P. aeruginosa.

Purpose of the Study:

  • To investigate the role of GrxD in P. aeruginosa antibiotic resistance.
  • To determine if GrxD is a potential target for enhancing polymyxin efficacy.

Main Methods:

  • Construction and analysis of a P. aeruginosa ΔgrxD mutant strain.
  • Site-directed mutagenesis of the grxD gene to identify key residues.
  • Testing polymyxin B susceptibility under various conditions (aerobic, anaerobic, iron chelation).

Main Results:

  • The ΔgrxD mutant exhibited significantly increased susceptibility to polymyxin B compared to wild-type.
  • The C29 residue in GrxD's active site is crucial for polymyxin resistance.
  • Increased susceptibility was observed regardless of oxygen or iron availability, suggesting a mechanism independent of hydroxyl radicals.

Conclusions:

  • GrxD plays a significant role in P. aeruginosa resistance to polymyxin B.
  • The C29 residue is essential for GrxD's protective function.
  • GrxD represents a promising therapeutic target for overcoming MDR P. aeruginosa infections with polymyxins.
Keywords:
Monothiol glutaredoxinPolymyxinsPseudomonas aeruginosa

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