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Curr Microbiol. 1998 Feb;36(2):96-101.

Characteristics and DNA-sequence of a cryptic haloalkanoic acid dehalogenase from Agrobacterium tumefaciens RS5.

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Department of Microbiology, FB19, University Gesamthochschule Kassel, Heinrich-Plett-Str. 40, D-34109 Kassel, Germany.


Agrobacterium tumefaciens RS5 harbors two different hydrolytic haloalkanoic acid dehalogenase genes, one coding for a nonstereospecific enzyme (DhlS5II) and a second for a cryptic L-isomer-specific dehalogenase (DhlS5I). The latter gene was cloned and expressed in Escherichia coli. Biochemical characterization and sequence analysis of dhlS5I shows its membership to the class of the L-isomer-specific hydrolytic dehalogenases. Highest homology of 72% was found to the dehalogenase LdexYL from Pseudomonas sp. YL. Both enzymes share an unusual high temperature optimum of 65 degrees C. Controlled by a vector promoter, high specific dehalogenase activities up to 32 U mg-1 protein were obtained in E. coli, and putatively, owing to its own sigma70-dependent promoter, a constitutive low-level expression of dhlS5I of 0.4 U mg-1 protein was measured.

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