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Outer membrane translocation of pyocins via the copper regulated TonB-dependent transporter CrtA

Jiraphan Premsuriya1,2, Khedidja Mosbahi1, Iva Atanaskovic3

  • 1School of Infection and Immunity, University of Glasgow, Glasgow G12 8TA, U.K.

The Biochemical Journal
|July 3, 2023
PubMed

Insights

Two novel pyocins, SX1 and SX2, from Pseudomonas aeruginosa were identified. These pyocins target multi-drug resistant strains by utilizing a unique copper-regulated transporter, CrtA, for cellular entry.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Pseudomonas aeruginosa causes severe hospital-acquired infections and is a leading cause of mortality in cystic fibrosis patients.
  • High antimicrobial resistance in P. aeruginosa necessitates novel therapeutic strategies.
  • Pyocins are protein antibiotics produced by P. aeruginosa that exhibit narrow-spectrum activity against the same species.

Purpose of the Study:

  • To identify and characterize novel pyocins from P. aeruginosa.
  • To elucidate the uptake and transport mechanisms of these novel pyocins.
  • To investigate the regulation and identify the transporter involved in pyocin uptake.

Main Methods:

  • Isolation and characterization of novel pyocins SX1 and SX2.
  • Analysis of pyocin activity (DNase and protein synthesis inhibition).
  • Genetic and biochemical methods to map pyocin uptake pathways, including the identification of a novel TonB-dependent transporter (TBDT).

Main Results:

  • Two novel S-type pyocins, SX1 (metal-dependent DNase) and SX2 (protein synthesis inhibitor), were identified.
  • Both pyocins utilize the common polysaccharide antigen (CPA) and a novel TBDT, PA0434 (designated CrtA), for outer membrane traversal.
  • TonB1 and FtsH are essential for pyocin energization and inner membrane translocation.
  • CrtA expression is regulated by copper availability.

Conclusions:

  • Novel pyocins SX1 and SX2 represent potential therapeutics against multi-drug resistant P. aeruginosa.
  • The identified uptake pathway involving CPA, CrtA, TonB1, and FtsH provides new insights into P. aeruginosa outer membrane transport.
  • The discovery of a TBDT (CrtA) not involved in iron uptake expands the known repertoire of bacterial transport systems.
Keywords:
Pseudomonas aeruginosaantibiotic resistancebacteriocinpyocin

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