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          Institute: MPI für marine Mikrobiologie     Collection: Abteilung Mikrobiologie     Display Documents



ID: 13926.0, MPI für marine Mikrobiologie / Abteilung Mikrobiologie
Genes involved in the anaerobic degradation of ethylbenzene in a denitrifying bacterium, strain EbN1
Authors:Rabus, R.; Kube, M.; Beck, A.; Widdel, F.; Reinhardt, R.
Language:English
Date of Publication (YYYY-MM-DD):2002-12
Title of Journal:Archives of Microbiology
Journal Abbrev.:Arch. Microbiol.
Volume:178
Issue / Number:6
Start Page:506
End Page:516
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Genes involved in anaerobic degradation of the petroleum hydrocarbon ethylbenzene in the denitrifying Azoarcus-like strain EbN1 were identified on a 56-kb DNA contig obtained from shotgun sequencing. Ethylbenzene is first oxidized via ethylbenzene dehydrogenase to (S)-1-phenylethanol; this is converted by (S)-1-phenylethanol dehydrogenase to acetophenone. Further degradation probably involves acetophenone carboxylase forming benzoylacetate, a ligase forming benzoylacetyl-CoA, and a thiolase forming acetyl-CoA and benzoyl-CoA. Genes of this pathway were identified via N-terminal sequences of proteins isolated from strain EbN1 and by sequence similarities to proteins from other bacteria. Ethylbenzene dehydrogenase is encoded by three genes (ebdABC), in accordance with the heterotrimeric enzyme structure. Binding domains for a molybdenum cofactor (in subunit EbdA) and iron/sulfur-clusters (in subunits EbdA and EbdB) were identified. The previously observed periplasmic location of the enzyme was corroborated by the presence of a twin-arginine leader peptide characteristic of the Tat system for protein export. A fourth gene (ebdD) was identified, the product of which may act as an enzyme-specific chaperone in the maturation of the molybdenum-containing subunit. A distinct gene (ped) coding for (S)(-1) phenylethanol dehydrogenase apparently forms an operon with the ebdABCD genes. The ped gene product with its characteristic NAD(P)- binding motif in the N-terminal domain belongs to the short- chain dehydrogenase/reductase (SDR) superfamily. A further operon apparently contains five genes (apc1-5) suggested to code for subunits of acetophenone carboxylase. Four of the five gene prod-ucts are similar to subunits of acetone carboxylase from Xanthobacter autotrophicus. Upstream of the apc genes, a single gene (bal) was identified which possibly codes for a benzoylacetate CoA-ligase and which is co-transcribed with the apc genes. In addition, an apparent operon containing almost all genes required for beta-oxidation of fatty acids was detected; one of the gene products may be involved in thiolytic cleavage of benzoylacetyl-CoA. The DNA fragment also included genes for regulatory systems; these were two sets of two- component systems, two LysR homologs, and a TetR homolog. Some of these proteins may be involved in ethylbenzene-dependent gene expression.
Free Keywords:ethylbenzene; denitrifying bacterium; anaerobic degradation; gene prediction; gene annotation; genomics
Comment of the Author/Creator:Date: 2002, DEC
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für marine Mikrobiologie
External Affiliations:Max Planck Inst Marine Mikrobiol, Celsiusstr 1, D-28359 Bremen,; Germany; Max Planck Inst Marine Mikrobiol, D-28359 Bremen, Germany; Max Planck Inst Mol Genet, D-14195 Berlin, Germany
Identifiers:ISI:000179674200018 [ID No:1]
ISSN:0302-8933 [ID No:2]
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