Functional characterization and molecular modeling of methylcatechol 2,3-dioxygenase from o-xylene-degrading Rhodococcus sp. strain DK17

Dockyu Kim, Jong Chan Chae, Jung Yeon Jang, Gerben J. Zylstra, Young Min Kim, Beom Sik Kang, Eungbin Kim

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Rhodococcus sp. strain DK17 is known to metabolize o-xylene and toluene through the intermediates 3,4-dimethylcatechol and 3- and 4-methylcatechol, respectively, which are further cleaved by a common catechol 2,3-dioxygenase. A putative gene encoding this enzyme (akbC) was amplified by PCR, cloned, and expressed in Escherichia coli. Assessment of the enzyme activity expressed in E. coli combined with sequence analysis of a mutant gene demonstrated that the akbC gene encodes the bona fide catechol 2,3-dioxygenase (AkbC) for metabolism of o-xylene and alkylbenzenes such as toluene and ethylbenzene. Analysis of the deduced amino acid sequence indicates that AkbC consists of a new catechol 2,3-dioxygenase class specific for methyl-substituted catechols. A computer-aided molecular modeling studies suggest that amino acid residues (particularly Phe177) in the β10-β11 loop play an essential role in characterizing the substrate specificity of AkbC.

Original languageEnglish
Pages (from-to)880-886
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number4
Publication statusPublished - 2005 Jan 28


All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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