Chlorocatechol dioxygenases

Mars AE, J Kingma, SR Kaschabek, W Reineke, DB Janssen (1999) Conversion of 3-chlorocatechol by various catechol 2,3-dioxygenases and sequence analysis of the chlorocatechol dioxygenase region of Pseudomonas putida GJ31. J Bacterial 181 1309-1318. 

Shimizu M, T Kimura, T Koyama, K Suzuki, N Ogawa, K Miyashita, K Dakka, K Ohmiya (2002) Molecular breeding of transgenic rice plants expressing a bacterial chlorocatechol dioxygenase gene. Appl Environ Microbiol 68 4061-4066. 

Chlorocatechol dioxygenase Increased for 3-chlorocatechol Increased for 3- chlorocatechol... 

Chlorocatechol dioxygenase tcbC, clcA, tfdC) Cycloisomerases (tc6D, c/cB, tfdD) a ORF3... 

Kaschabek SR, T Kasberg, D Muller, AE Mars, DB Janssen, W Reineke (1998) Degradation of chloroaromat-ics purification and characterization of a novel type of chlorocatechol 2,3-dioxygenase of Pseudomonas putida GJ31. J Bacterial 180 296-302. 

C subfamily of type 1 extradiol dioxygenases (Mars et al. 1999). The alternative extradiol fission of 3-chlorocatechol may take place between the 1 and 6 positions (distal fission), and this has been shown for the 2,3-dihydroxybiphenyl 1,2-dioxygenase from the naphthalene sulfonate degrading Sphingomonas sp. strain BN6 (Riegert et al. 1998). 

Riegert U, G Heiss, P Fischer, A Stolz (1998) Distal cleavage of 3-chlorocatechol by an extradiol dioxygenase to 3-chloro-2-hydroxymuconic semialdehyde. J Bacterial 180 2849-2853. 

Potrawfke T, J Armangaud, R-M Wittich (2001) Chlorocatechols substituted at positions 4 and 5 are substrates of the broad-spectrum chlorocatechol 1,2-dioxygenase of Pseudomonas chlororaphis RW71. J Bacteriol 183 997-1011. 

Ralstonia eutropha (Alcaligenes eutrophus) strain NH9 is able to degrade 3-chlorobenzene by the modified ortho pathway. The cbnA gene that encodes 3-chlorocatechol-l, 2-dioxygenase was introduced into rice plants (Oryza sativa -p.japonicd) under the control of a virus 35S promoter. 3-Chlorocatechol induced dioxygenase activity in the callus of the plants, and leaf tissues oxidized 3-chlorocatechol with the production of 2-chloromuconate... 

Although the possibly incompatible pathways for the degradation of chlorobenzene and toluene has been noted, a strain of Ralstonia sp. from a site contaminated with chlorobenzene contained the genes for both chlorocatechol degradation and the dioxygenase system for the degradation of benzene/toluene (van der Meer et al. 1998). The evolution of this strain resulted in a natural lowering... 

Contaminated soil has been inoculated with bacteria of established capacity for degradation of chlorobenzoates (Hickey et al. 1993). In the presence of added biphenyl, mineralization of PCBs was shown, although it was pointed out that there may exist incompatibility between the prodnction of chlorocatechols from chlorobenzoates and their inhibition of dihydroxybiphenyl-2,3-dioxygenase that catalyzes the ring fission of many PCBs. 

Ralstonia eutropha has the ability to use 3-chlorobenzoate as carbon source, and an important step in the pathway is the enzyme chlorocatechol 1,2-dioxygenase, encoded by the gene cbnA. This gene has been introduced into rice calli and plants under the control of the CaMV 35S promoter (Shimizu et al., 2002). In transgenic leaf tissues, the conversion of 3-chlorocatechol into 2-chloromuconate was time-dependent. A decrease in the level of the compound present was also observed in control plants, but this was due to adsorption as no metabolites were detected. 

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