title: Functional characterization of a gene cluster involved in gentisate catabolism in Rhodococcus sp. strain NCIMB 12038.
abstract: Rhodococcus sp. strain NCIMB 12038 utilizes naphthalene as a sole source of carbon and energy, and degrades naphthalene via salicylate and gentisate. To identify the genes involved in this pathway, we cloned and sequenced a 12-kb DNA fragment containing a gentisate catabolic gene cluster. Among the 13 complete open reading frames deduced from this fragment, three (narIKL) have been shown to encode the enzymes involved in the reactions of gentisate catabolism. NarI is gentisate 1,2-dioxygenase which converts gentisate to maleylpyruvate, NarL is a mycothiol-dependent maleylpyruvate isomerase which catalyzes the isomerization of maleylpyruvate to fumarylpyruvate, and NarK is a fumarylpyruvate hydrolase which hydrolyzes fumarylpyruvate to fumarate and pyruvate. The narX gene, which is divergently transcribed with narIKL, has been shown to encode a functional 3-hydroxybenzoate 6-monooxygenase. This led us to discover that this strain is also capable of utilizing 3-hydroxybenzoate as its sole source of carbon and energy. Both NarL and NarX were purified to homogeneity as His-tagged proteins, and they were determined by gel filtration to exist as a trimer and a monomer, respectively. Our study suggested that the gentisate degradation pathway was shared by both naphthalene and 3-hydroxybenzoate catabolism in this strain.
authors.affiliation: CAS Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Sha
authors.initials: S
authors.lastname: Luo
authors.forename: Ya-Jie
authors.initials: YJ
authors.lastname: Yin
authors.forename: Shuang-Jiang
authors.initials: SJ
authors.lastname: Liu
authors.forename: Ning-Yi
authors.initials: NY
authors.lastname: Zhou
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D005841:Gentisates / Q000378:metabolism*; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics; D005810:Multigene Family; D009281:Naphthalenes / Q000378:metabolism*; D010867:Pimelic Acids / Q000378:metabolism; D012240:Rhodococcus / Q000201:enzymology* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D005841:Gentisates; D009097:Multienzyme Complexes; D009281:Naphthalenes; D010867:Pimelic Acids; C113957:maleylpyruvic acid; C031721:naphthalene; D006899:Mixed Function Oxygenases; D049308:Dioxygenases; C026247:gentisate 1,2-dioxygenase; C023315:3-hydroxybenzoate-6-hydroxylase; D006867:Hydrolases; C026249:fumarylpyruvate hydrolase