Affiliation:
1. Microbial Interactions and Processes Research Group, HZI–Helmholtz Centre for Infection Research, Braunschweig, Germany
Abstract
ABSTRACT
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.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
17 articles.
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