Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile.
PLoS One. 2011 Mar 10;6(3):e17583. doi: 10.1371/journal.pone.0017583.
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.
METHODOLOGY/PRINCIPAL FINDINGS: 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/SIGNIFICANCE: 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.
模式 PCB 降解菌伯克霍尔德氏菌 LB400 的基因组特征表明，芳香族化合物降解存在 11 条中心途径，其中包括 homogentisate 和 homoprotocatechuate 途径。然而，LB400 菌株中这些中心途径的功能尚未得到评估，相关的周边途径也尚未描述。
方法/主要发现：本研究的目的是确定 B. xenovorans LB400 中 homogentisate 和 homoprotocatechuate 中心途径的功能，并确定它们在 3-羟基苯乙酸（3-HPA）和 4-羟基苯乙酸（4-HPA）代谢中的作用。LB400 能够以 3-HPA 和 4-HPA 作为唯一碳源生长。在 LB400 中的基因组搜索表明存在编码 3-羟基苯乙酸和 4-羟基苯乙酸周边途径蛋白的 mhaAB 和 hpaBC 基因簇。用 3-HPA 和 4-HPA 培养的 LB400 细胞降解 homogentisate 和 homoprotocatechuate，并表现出 homogentisate 1,2-双加氧酶和 homoprotocatechuate 2,3-双加氧酶活性。通过 RT-PCR 的转录分析显示，在 3-HPA 和 4-HPA 降解过程中，两个染色体编码的 homogentisate 双加氧酶（BxeA2725 和 BxeA3900）和编码 homoprotocatechuate 2,3-双加氧酶的 hpaD 基因表达。用二维聚丙烯酰胺凝胶电泳对 B. xenovorans LB400 在 3-HPA 和 4-HPA 中生长的蛋白质组分析表明，诱导了 fumarylacetoacetate hydrolase HmgB（BxeA3899）。
结论/意义：本研究表明，LB400 菌株既利用 homogentisate 又利用 homoprotocatechuate 环裂解途径进行 3-羟苯基乙酸和 4-羟苯基乙酸代谢，并且这四条代谢途径是功能性的，证实了 B. xenovorans LB400 的代谢多功能性。
