Identification of a novel dioxygenase involved in metabolism of o-xylene, toluene, and ethylbenzene by Rhodococcus sp. strain DK17

Dockyu Kim, Jong Chan Chae, Gerben J. Zylstra, Young Soo Kim, Seong Ki Kim, Hee Nam Myung, Min Kim Young, Eungbin KIm

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the OMFs, we identified two nearly exact copies (one base difference) of genes encoding large and small subunits of an iron sulfur protein terminal oxygenase that are 6 kb apart from each other. Immediateiy downstream of one copy of the dioxygenase genes (akbA1a and akbA2a) is a gene encoding a dioxygenase ferredoxin component (akbA3), and downstream of the other copy (akbA1b and akbA2b) are genes putatively encoding a meta-cleavage pathway. RT-PCR experiments show that the two copies of the dioxygenase genes are operonic with the downstream putative catabolic genes and that both operons are induced by o-xylene. When expressed in Escherichia coli, AkbA1a-AkbA2a-AkbA3 transformed o-xylene into 2,3- and 3,4-dimethylphenol. These were apparently derived from an unstable o-xylene cis-3,4-dihydrodiol, which readily dehydrates. This indicates a single point of attack of the dioxygenase on the aromatic ring. In contrast, attack of AkbA1a-AkbA2a-AkbA3 on ethylbenzene resulted in the formation of two different cis-dihydrodiols resulting from an oxidation at the 2,3 and the 3,4 positions on the aromatic ring, respectively.

Original languageEnglish
Pages (from-to)7086-7092
Number of pages7
JournalApplied and Environmental Microbiology
Volume70
Issue number12
DOIs
Publication statusPublished - 2004 Dec 1

Fingerprint

Rhodococcus
xylene
Dioxygenases
toluene
Toluene
metabolism
gene
Genes
genes
aromatic compounds
sulfur proteins
Iron-Sulfur Proteins
Ferredoxins
Oxygenases
Cosmids
ferredoxins
BTEX
ethylbenzene
2-xylene
benzene

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

Kim, Dockyu ; Chae, Jong Chan ; Zylstra, Gerben J. ; Kim, Young Soo ; Kim, Seong Ki ; Myung, Hee Nam ; Young, Min Kim ; KIm, Eungbin. / Identification of a novel dioxygenase involved in metabolism of o-xylene, toluene, and ethylbenzene by Rhodococcus sp. strain DK17. In: Applied and Environmental Microbiology. 2004 ; Vol. 70, No. 12. pp. 7086-7092.
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abstract = "Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the OMFs, we identified two nearly exact copies (one base difference) of genes encoding large and small subunits of an iron sulfur protein terminal oxygenase that are 6 kb apart from each other. Immediateiy downstream of one copy of the dioxygenase genes (akbA1a and akbA2a) is a gene encoding a dioxygenase ferredoxin component (akbA3), and downstream of the other copy (akbA1b and akbA2b) are genes putatively encoding a meta-cleavage pathway. RT-PCR experiments show that the two copies of the dioxygenase genes are operonic with the downstream putative catabolic genes and that both operons are induced by o-xylene. When expressed in Escherichia coli, AkbA1a-AkbA2a-AkbA3 transformed o-xylene into 2,3- and 3,4-dimethylphenol. These were apparently derived from an unstable o-xylene cis-3,4-dihydrodiol, which readily dehydrates. This indicates a single point of attack of the dioxygenase on the aromatic ring. In contrast, attack of AkbA1a-AkbA2a-AkbA3 on ethylbenzene resulted in the formation of two different cis-dihydrodiols resulting from an oxidation at the 2,3 and the 3,4 positions on the aromatic ring, respectively.",
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Identification of a novel dioxygenase involved in metabolism of o-xylene, toluene, and ethylbenzene by Rhodococcus sp. strain DK17. / Kim, Dockyu; Chae, Jong Chan; Zylstra, Gerben J.; Kim, Young Soo; Kim, Seong Ki; Myung, Hee Nam; Young, Min Kim; KIm, Eungbin.

In: Applied and Environmental Microbiology, Vol. 70, No. 12, 01.12.2004, p. 7086-7092.

Research output: Contribution to journalArticle

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T1 - Identification of a novel dioxygenase involved in metabolism of o-xylene, toluene, and ethylbenzene by Rhodococcus sp. strain DK17

AU - Kim, Dockyu

AU - Chae, Jong Chan

AU - Zylstra, Gerben J.

AU - Kim, Young Soo

AU - Kim, Seong Ki

AU - Myung, Hee Nam

AU - Young, Min Kim

AU - KIm, Eungbin

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