JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Seffernick, J. L.
Right arrow Articles by Wackett, L. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Seffernick, J. L.
Right arrow Articles by Wackett, L. P.

Journal of Bacteriology, April 2001, p. 2405-2410, Vol. 183, No. 8
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.8.2405-2410.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

Melamine Deaminase and Atrazine Chlorohydrolase: 98 Percent Identical but Functionally Different

Jennifer L. Seffernick,1,2 Mervyn L. de Souza,1,2,dagger Michael J. Sadowsky,1,2,3,4 and Lawrence P. Wackett1,2,3,*

Department of Biochemistry, Molecular Biology, and Biophysics,1 Biological Process Technology Institute,3 Center for Microbial and Plant Genomics,2 and Department of Soil, Water, and Climate,4 University of Minnesota, St. Paul, Minnesota 55108

Received 12 October 2000/Accepted 22 January 2001

The gene encoding melamine deaminase (TriA) from Pseudomonas sp. strain NRRL B-12227 was identified, cloned into Escherichia coli, sequenced, and expressed for in vitro study of enzyme activity. Melamine deaminase displaced two of the three amino groups from melamine, producing ammeline and ammelide as sequential products. The first deamination reaction occurred more than 10 times faster than the second. Ammelide did not inhibit the first or second deamination reaction, suggesting that the lower rate of ammeline hydrolysis was due to differential substrate turnover rather than product inhibition. Remarkably, melamine deaminase is 98% identical to the enzyme atrazine chlorohydrolase (AtzA) from Pseudomonas sp. strain ADP. Each enzyme consists of 475 amino acids and differs by only 9 amino acids. AtzA was shown to exclusively catalyze dehalogenation of halo-substituted triazine ring compounds and had no activity with melamine and ammeline. Similarly, melamine deaminase had no detectable activity with the halo-triazine substrates. Melamine deaminase was active in deamination of a substrate that was structurally identical to atrazine, except for the substitution of an amino group for the chlorine atom. Moreover, melamine deaminase and AtzA are found in bacteria that grow on melamine and atrazine compounds, respectively. These data strongly suggest that the 9 amino acid differences between melamine deaminase and AtzA represent a short evolutionary pathway connecting enzymes catalyzing physiologically relevant deamination and dehalogenation reactions, respectively.

* Corresponding author. Mailing address: Department of Biochemistry, Molecular Biology, and Biophysics, 1479 Gortner Ave., University of Minnesota, St. Paul, MN 55108. Phone: (612) 625-3785. Fax: (612) 625-1700. E-mail: wackett{at}biosci.cbs.umn.edu.

dagger Present address: Cargill, Inc., Minneapolis, MN 55440-5702.

Journal of Bacteriology, April 2001, p. 2405-2410, Vol. 183, No. 8
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.8.2405-2410.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 2001 by the American Society for Microbiology. All rights reserved.