title: The homogentisate and homoprotocatechuate central pathways are involved in 3- and 4-hydroxyphenylacetate degradation by Burkholderia xenovorans LB400.
abstract: BACKGROUND
  Genome characterization of the model PCB-degrading bacterium Burkholderia xenovorans LB400 revealed the presence of eleven central pathways for aromatic compounds degradation, among them, the homogentisate and the homoprotocatechuate pathways. However, the functionality of these central pathways in strain LB400 has not been assessed and related peripheral pathways has not been described.
  
  
  RESULTS
  The aims of this study were to determine the functionality of the homogentisate and homoprotocatechuate central pathways in B. xenovorans LB400 and to establish their role in 3-hydroxyphenylacetate (3-HPA) and 4-hydroxyphenylacetate (4-HPA) catabolism. Strain LB400 was able to grow using 3-HPA and 4-HPA as sole carbon source. A genomic search in LB400 suggested the presence of mhaAB and hpaBC genes clusters encoding proteins of the 3-hydroxyphenylacetate and 4-hydroxyphenylacetate peripheral pathways. LB400 cells grown with 3-HPA and 4-HPA degraded homogentisate and homoprotocatechuate and showed homogentisate 1,2-dioxygenase and homoprotocatechuate 2,3-dioxygenase activities. Transcriptional analyses by RT-PCR showed the expression of two chromosomally-encoded homogentisate dioxygenases (BxeA2725 and BxeA3900) and the hpaD gene encoding the homoprotocatechuate 2,3-dioxygenase during 3-HPA and 4-HPA degradation. The proteome analyses by two-dimensional polyacrilamide gel electrophoresis of B. xenovorans LB400 grown in 3-HPA and 4-HPA showed the induction of fumarylacetoacetate hydrolase HmgB (BxeA3899).
  
  
  CONCLUSIONS
  This study revealed that strain LB400 used both homogentisate and homoprotocatechuate ring-cleavage pathways for 3- hydroxyphenylacetate and 4-hydroxyphenylacetate catabolism and that these four catabolic routes are functional, confirming the metabolic versatility of B. xenovorans LB400.
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile.
authors.forename: Valentina
authors.initials: V
authors.lastname: Méndez
authors.forename: Loreine
authors.initials: L
authors.lastname: Agulló
authors.forename: Myriam
authors.initials: M
authors.lastname: González
authors.forename: Michael
authors.initials: M
authors.lastname: Seeger
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism* / Q000494:pharmacology; D001673:Biodegradation, Environmental / Q000187:drug effects; D019117:Burkholderia / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D006713:Homogentisic Acid / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D008954:Models, Biological; D005810:Multigene Family / Q000235:genetics; D010648:Phenylacetates / Q000378:metabolism*; D010802:Phylogeny; D040901:Proteomics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C026245:3-hydroxyphenylacetate; D010648:Phenylacetates; D015102:3,4-Dihydroxyphenylacetic Acid; C026246:4-hydroxyphenylacetate; D006713:Homogentisic Acid