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首页> 外文期刊>Journal of bacteriology >Degradation of 2,3-Dihydroxybenzoate by a Novel meta-Cleavage Pathway
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Degradation of 2,3-Dihydroxybenzoate by a Novel meta-Cleavage Pathway

机译:新型的元裂解途径降解2,3-二羟基苯甲酸酯

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2,3-Dihydroxybenzoate is the precursor in the biosynthesis of several siderophores and an important plant secondary metabolite that, in bacteria, can be degraded via meta-cleavage of the aromatic ring. The dhb cluster of Pseudomonas reinekei MT1 encodes a chimeric meta-cleavage pathway involved in the catabolism of 2,3-dihydroxybenzoate. While the first two enzymes, DhbA and DhbB, are phylogenetically related to those involved in 2,3-dihydroxy-p-cumate degradation, the subsequent steps are catalyzed by enzymes related to those involved in catechol degradation (DhbCDEFGH). Characterization of kinetic properties of DhbA extradiol dioxygenase identified 2,3-dihydroxybenzoate as the preferred substrate. Deletion of the encoding gene impedes growth of P. reinekei MT1 on 2,3-dihydroxybenzoate. DhbA catalyzes 3,4-dioxygenation with 2-hydroxy-3-carboxymuconate as the product, which is then decarboxylated by DhbB to 2-hydroxymuconic semialdehyde. This compound is then subject to dehydrogenation and further degraded to citrate cycle intermediates. Transcriptional analysis revealed genes of the dhB gene cluster to be highly expressed during growth with 2,3-dihydroxybenzoate, whereas a downstream-localized gene encoding 2-hydroxymuconic semialdehyde hydrolase, dispensable for 2,3-dihydroxybenzoate metabolism but crucial for 2,3-dihydroxy-p-cumate degradation, was only marginally expressed. This is the first report describing a gene cluster encoding enzymes for the degradation of 2,3-dihydroxybenzoate.
机译:2,3-二羟基苯甲酸酯是几种铁载体生物合成中的前体,并且是一种重要的植物次生代谢产物,在细菌中,可以通过芳环的 meta 裂解而降解。假单胞菌MT1的 dhb 簇编码参与2,3-二羟基苯甲酸酯分解代谢的嵌合 meta 裂解途径。虽然前两种酶DhbA和DhbB与2,3-二羟基- p -累积酸酯降解相关,但随后的步骤却被与邻苯二酚降解相关的酶催化( DhbCDEFGH)。 DhbA外二醇双加氧酶的动力学特性的表征确定2,3-二羟基苯甲酸酯为首选底物。编码基因的删除阻碍了P.reinekei MT1在2,3-二羟基苯甲酸酯上的生长。 DhbA用2-羟基-3-羧基粘康酸酯作为产物催化3,4-二加氧,然后通过DhbB脱羧成2-羟基粘康半醛。然后使该化合物脱氢并进一步降解为柠檬酸盐循环中间体。转录分析显示, dhB 基因簇的基因在2,3-二羟基苯甲酸酯的生长过程中高度表达,而下游定位的编码2-羟基粘康半醛水解酶的基因可用于2,3-二羟基苯甲酸酯的代谢但是对于2,3-二羟基- p -累积的降解至关重要,只是微不足道。这是第一个描述编码2,3-二羟基苯甲酸酯降解酶的基因簇的报告。

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