A functional phenylacetic acid catabolic pathway is required for full pathogenicity of Burkholderia cenocepacia in the Caenorhabditis elegans host model

J Bacteriol. 2008 Nov;190(21):7209-18. doi: 10.1128/JB.00481-08. Epub 2008 Sep 5.


Burkholderia cenocepacia is a member of the Burkholderia cepacia complex, a group of metabolically versatile bacteria that have emerged as opportunistic pathogens in cystic fibrosis and immunocompromised patients. Previously a screen of transposon mutants in a rat pulmonary infection model identified an attenuated mutant with an insertion in paaE, a gene related to the phenylacetic acid (PA) catabolic pathway. In this study, we characterized gene clusters involved in the PA degradation pathway of B. cenocepacia K56-2 in relation to its pathogenicity in the Caenorhabditis elegans model of infection. We demonstrated that targeted-insertion mutagenesis of paaA and paaE, which encode part of the putative PA-coenzyme A (CoA) ring hydroxylation system, paaZ, coding for a putative ring opening enzyme, and paaF, encoding part of the putative beta-oxidation system, severely reduces growth on PA as a sole carbon source. paaA and paaE insertional mutants were attenuated for virulence, and expression of paaE in trans restored pathogenicity of the paaE mutant to wild-type levels. Interruption of paaZ and paaF slightly increased virulence. Using gene interference by ingested double-stranded RNA, we showed that the attenuated phenotype of the paaA and paaE mutants is dependent on a functional p38 mitogen-activated protein kinase pathway in C. elegans. Taken together, our results demonstrate that B. cenocepacia possesses a functional PA degradation pathway and that the putative PA-CoA ring hydroxylation system is required for full pathogenicity in C. elegans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Burkholderia cepacia / genetics*
  • Burkholderia cepacia / metabolism
  • Burkholderia cepacia / pathogenicity
  • Caenorhabditis elegans / microbiology*
  • Gene Expression Regulation, Bacterial
  • Host-Pathogen Interactions
  • Intestines / microbiology
  • Models, Genetic
  • Molecular Sequence Data
  • Multigene Family / genetics
  • Mutagenesis, Insertional
  • Phenylacetates / metabolism*
  • Virulence / genetics


  • Bacterial Proteins
  • Phenylacetates
  • phenylacetic acid

Associated data

  • GENBANK/EU606014