A functional phenylacetic acid catabolic pathway is required for full pathogenicity of Burkholderia cenocepacia in the Caenorhabditis elegans host model.
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.
Law
Robyn J
RJ
Department of Microbiology, Buller Building, Room 418, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
Hamlin
Jason N R
JN
Sivro
Aida
A
McCorrister
Stuart J
SJ
Cardama
Georgina A
GA
Cardona
Silvia T
ST
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016956:Burkholderia cepacia / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D017173:Caenorhabditis elegans / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D007422:Intestines / Q000382:microbiology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D016254:Mutagenesis, Insertional; D010648:Phenylacetates / Q000378:metabolism*; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D010648:Phenylacetates; C025136:phenylacetic acid
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