Binding of protegrin-1 to Pseudomonas aeruginosa and Burkholderia cepacia

Albrecht, Wang Wei, Shamova Olga, Lehrer, Schiller

Description

Pseudomonas aeruginosa and Burkholderia cepacia infections of cystic fibrosis patients' lungs are often resistant to conventional antibiotic therapy. Protegrins are antimicrobial peptides with potent activity against many bacteria, including P. aeruginosa . The present study evaluates the correlation between protegrin-1 (PG-1) sensitivity/resistance and protegrin binding in P. aeruginosa and B. cepacia . Methods The PG-1 sensitivity/resistance and PG-1 binding properties of P. aeruginosa and B. cepacia were assessed using radial diffusion assays, radioiodinated PG-1, and surface plasmon resonance (BiaCore). Results The six P. aeruginosa strains examined were very sensitive to PG-1, exhibiting minimal active concentrations from 0.0625–0.5 μg/ml in radial diffusion assays. In contrast, all five B. cepacia strains examined were greater than 10-fold to 100-fold more resistant, with minimal active concentrations ranging from 6–10 μg/ml. When incubated with a radioiodinated variant of PG-1, a sensitive P. aeru ginosa strain bound considerably more protegrin molecules per cell than a resistant B. cepacia strain. Binding/diffusion and surface plasmon resonance assays revealed that isolated lipopolysaccharide (LPS) and lipid A from the sensitive P. aeruginosa strains bound PG-1 more effectively than LPS and lipid A from resistant B. cepacia strains. Conclusion These findings support the hypothesis that the relative resistance of B. cepacia to protegrin is due to a reduced number of PG-1 binding sites on the lipid A moiety of its LPS.

Sujets

• Burkholderia cepacia
• Lipid A
• Lipopolysaccharide
• Protegrin
• Pseudomonas aeruginosa

Informations

• Publié par: biomed
• Publié le: 01 janvier 2002
• Nombre de lectures: 7
• Langue: English

Extrait

Available onlinehttp://respiratoryresearch/content/3/1/18

atory Research R V e o s l p 1 3 ir 8 Res 3/1/ No 1 Respir Research article Binding of protegrin1 toPseudomonas aeruginosaand Burkholderia cepacia 1 22 2,31 Mark T Albrecht, Wei Wang, Olga Shamova, Robert I Lehrerand Neal L Schiller

1 Division of Biomedical Sciences, University of California, Riverside, California 92521, USA. 2 Department of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA. 3 Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California 90095, USA.

Correspondence:Neal L Schiller  [e-mail]

Received: 1 October 2001 Revisions requested: 19 November 2001 Revisions received: 29 January 2002 Accepted: 31 January 2002 Published: 14 March 2002

Respir Res2002,3:18

© 2002 Albrecht et al, licencee BioMed Central Ltd (Print ISSN 14659921; Online ISSN 1465993X)

Abstract Background:Pseudomonas aeruginosa andBurkholderia cepaciaof cystic fibrosis infections patients' lungs are often resistant to conventional antibiotic therapy. Protegrins are antimicrobial peptides with potent activity against many bacteria, includingP. aeruginosa. The present study evaluates the correlation between protegrin1 (PG1) sensitivity/resistance and protegrin binding inP. aeruginosaandB. cepacia. Methods:The PG1 sensitivity/resistance and PG1 binding properties ofP. aeruginosa andB. cepaciaassessed using radial diffusion assays, radioiodinated PG1, and surface plasmon were resonance (BiaCore). Results:The sixP. aeruginosastrains examined were very sensitive to PG1, exhibiting minimal active concentrations from 0.0625–0.5µg/ml in radial diffusion assays. In contrast, all fiveB. cepaciastrains examined were greater than 10fold to 100fold more resistant, with minimal active concentrations ranging from 6–10µg/ml. When incubated with a radioiodinated variant of PG1, a sensitiveP. aeruginosa strain bound considerably more protegrin molecules per cell than a resistantB. cepacia strain. Binding/diffusion and surface plasmon resonance assays revealed that isolated lipopolysaccharide (LPS) and lipid A from the sensitiveP. aeruginosa strainsbound PG1 more effectively than LPS and lipid A from resistantB. cepaciastrains. Conclusion:These findings support the hypothesis that the relative resistance ofB. cepacia to protegrin is due to a reduced number of PG1 binding sites on the lipid A moiety of its LPS.

Keywords:Burkholderia cepacia, lipid A, lipopolysaccharide, protegrin,Pseudomonas aeruginosa

Introduction Cystic fibrosis (CF) is a generalized exocrine disease re sulting from the defective regulation of epithelial chloride ion transport within various organ systems, most important ly the lungs [1–4]. This dysfunction can arise from a variety of mutations within the cystic fibrosis transmembrane con ductance regulator (CFTR) gene on chromosome 7, which encodes the transmembrane pump responsible for regulat ing transepithelial ion levels [1,2,4]. This defect is associat ed with an increased viscosity of the airway surface fluid, and according to some studies, an altered salt concentra

tion [5,6]. These and other pleiotropic effects of the CF gene abnormality increase the susceptibility of CF patients to bronchopulmonary bacterial infection by opportunistic pathogens.

Pseudomonas aeruginosais the most common pathogen recovered from the lungs of CF patients [2,3]. This predis position toP. aeruginosainfection has been attributed to several factors. For example, an increase in asialoGM 1 glycoproteins on the apical surface of CF airway epithelial cells provides greater opportunity for adhesion by the type

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