Previous Article | Next Article 
Journal of Bacteriology, January 2005, p. 415-421, Vol. 187, No. 2
0021-9193/05/$08.00+0 doi:10.1128/JB.187.2.415-421.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Evolutionarily Divergent Extradiol Dioxygenases Possess Higher Specificities for Polychlorinated Biphenyl Metabolites
Pascal D. Fortin,1,2
Andy T.-F. Lo,1
María-Amparo Haro,2,
Stefan R. Kaschabek,3,4
Walter Reineke,3 and
Lindsay D. Eltis1,2*
Departments of Microbiology and Biochemistry, University of British Columbia, Vancouver,1
Department of Biochemistry, Université Laval, Quebec City, Quebec, Canada,2
Bergische Universität Wuppertal, Chemische Mikrobiologie, Wuppertal,3
Technische-Universität Bergakademie Freiberg, Freiberg, Germany4
Received 16 September 2004/
Accepted 20 October 2004
The reactivities of four evolutionarily divergent extradiol dioxygenases towards mono-, di-, and trichlorinated (triCl) 2,3-dihydroxybiphenyls (DHBs) were investigated: 2,3-dihydroxybiphenyl dioxygenase (EC 1.13.11.39) from Burkholderia sp. strain LB400 (DHBDLB400), DHBDP6-I and DHBDP6-III from Rhodococcus globerulus P6, and 2,2',3-trihydroxybiphenyl dioxygenase from Sphingomonas sp. strain RW1 (THBDRW1). The specificity of each isozyme for particular DHBs differed by up to 3 orders of magnitude. Interestingly, the Kmapp values of each isozyme for the tested polychlorinated DHBs were invariably lower than those of monochlorinated DHBs. Moreover, each enzyme cleaved at least one of the tested chlorinated (Cl) DHBs better than it cleaved DHB (e.g., apparent specificity constants for 3',5'-dichlorinated [diCl] DHB were 2 to 13.4 times higher than for DHB). These results are consistent with structural data and modeling studies which indicate that the substrate-binding pocket of the DHBDs is hydrophobic and can accommodate the Cl DHBs, particularly in the distal portion of the pocket. Although the activity of DHBDP6-III was generally lower than that of the other three enzymes, six of eight tested Cl DHBs were better substrates for DHBDP6-III than was DHB. Indeed, DHBDP6-III had the highest apparent specificity for 4,3',5'-triCl DHB and cleaved this compound better than two of the other enzymes. Of the four enzymes, THBDRW1 had the highest specificity for 2'-Cl DHB and was at least five times more resistant to inactivation by 2'-Cl DHB, consistent with the similarity between the latter and 2,2',3-trihydroxybiphenyl. Nonetheless, THBDRW1 had the lowest specificity for 2',6'-diCl DHB and, like the other enzymes, was unable to cleave this critical PCB metabolite (kcatapp < 0.001 s–1).
* Corresponding author. Mailing address: Department of Microbiology and Immunology, University of British Columbia, #300-6174 University Blvd., Vancouver, BC V6T 1Z3, Canada. Phone: (604) 822-0042. Fax: (604) 822-6041. E-mail: leltis{at}interchange.ubc.ca.
Present address: Biotools, B & M Labs, S.A., E-28021 Madrid, Spain.
Journal of Bacteriology, January 2005, p. 415-421, Vol. 187, No. 2
0021-9193/05/$08.00+0 doi:10.1128/JB.187.2.415-421.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Patrauchan, M. A., Florizone, C., Eapen, S., Gomez-Gil, L., Sethuraman, B., Fukuda, M., Davies, J., Mohn, W. W., Eltis, L. D.
(2008). Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism in Rhodococcus jostii RHA1. J. Bacteriol.
190: 37-47
[Abstract]
[Full Text]
-
Van der Geize, R., Yam, K., Heuser, T., Wilbrink, M. H., Hara, H., Anderton, M. C., Sim, E., Dijkhuizen, L., Davies, J. E., Mohn, W. W., Eltis, L. D.
(2007). A gene cluster encoding cholesterol catabolism in a soil actinomycete provides insight into Mycobacterium tuberculosis survival in macrophages. Proc. Natl. Acad. Sci. USA
104: 1947-1952
[Abstract]
[Full Text]
-
Fortin, P. D., MacPherson, I., Neau, D. B., Bolin, J. T., Eltis, L. D.
(2005). Directed Evolution of a Ring-cleaving Dioxygenase for Polychlorinated Biphenyl Degradation. J. Biol. Chem.
280: 42307-42314
[Abstract]
[Full Text]
