Aminoarabinose is essential for lipopolysaccharide export and intrinsic antimicrobial peptide resistance in Burkholderia cenocepacia

Mohamad A Hamad, Flaviana Di Lorenzo, Antonio Molinaro, Miguel A Valvano

Research output: Contribution to journalArticlepeer-review

62 Citations (Scopus)

Abstract

One common mechanism of resistance against antimicrobial peptides in Gram-negative bacteria is the addition of 4-amino-4-deoxy-l-arabinose (l-Ara4N) to the lipopolysaccharide (LPS) molecule. Burkholderia cenocepacia exhibits extraordinary intrinsic resistance to antimicrobial peptides and other antibiotics. We have previously discovered that unlike other bacteria, B. cenocepacia requires l-Ara4N for viability. Here, we describe the isolation of B. cenocepacia suppressor mutants that remain viable despite the deletion of genes required for l-Ara4N synthesis and transfer to the LPS. The absence of l-Ara4N is the only structural difference in the LPS of the mutants compared with that of the parental strain. The mutants also become highly sensitive to polymyxin B and melittin, two different classes of antimicrobial peptides. The suppressor phenotype resulted from a single amino acid replacement (aspartic acid to histidine) at position 31 of LptG, a protein component of the multi-protein pathway responsible for the export of the LPS molecule from the inner to the outer membrane. We propose that l-Ara4N modification of LPS provides a molecular signature required for LPS export and proper assembly at the outer membrane of B. cenocepacia, and is the most critical determinant for the intrinsic resistance of this bacterium to antimicrobial peptides.
Original languageEnglish
Pages (from-to)962-974
Number of pages13
JournalMolecular Microbiology
Volume85
Issue number5
Early online date18 Jul 2012
DOIs
Publication statusPublished - Sep 2012

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

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