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Applied and Environmental Microbiology, October 2001, p. 4603-4609, Vol. 67, No. 10
Department of Soil
Science1 and Environmental Toxicology
Center,2 University of Wisconsin
Received 16 April 2001/Accepted 31 July 2001
We have identified in Pseudomonas aeruginosa strain
JB2 a novel cluster of mobile genes encoding degradation of hydroxy-
and halo-aromatic compounds. Nineteen open reading frames were located and, based on sequence similarities, were putatively identified as
encoding a ring hydroxylating oxygenase (hybABCD), an
ATP-binding cassette-type transporter, an extradiol ring-cleavage
dioxygenase, transcriptional regulatory proteins, enzymes mediating
chlorocatechol degradation, and transposition functions. Expression of
hybABCD in Escherichia coli cells
effected stoichiometric transformation of 2-hydroxybenzoate
(salicylate) to 2,5-dihydroxybenzoate (gentisate). This activity was
predicted from sequence similarity to functionally characterized genes,
nagAaGHAb from Ralstonia sp. strain U2
(S. L. Fuenmayor, M. Wild, A. L. Boyes, and P. A. Williams, J. Bacteriol. 180:2522-2530, 1998), and is the second
confirmed example of salicylate 5-hydroxylase activity effected by an
oxygenase outside the flavoprotein group. Growth of strain JB2 or
Pseudomonas huttiensis strain D1 (an organism that had
acquired the 2-chlorobenzoate degradation phenotype from strain JB2) on
benzoate yielded mutants that were unable to grow on salicylate or
2-chlorobenzoate and that had a deletion encompassing
hybABCD and the region cloned downstream. The mutants'
inability to grow on 2-chlorobenzoate suggested the loss of additional
genes outside of, but contiguous with, the characterized region.
Pulsed-field gel electrophoresis revealed a plasmid of >300 kb in
strain D1, but no plasmids were detected in strain JB2. Hybridization
analyses confirmed that the entire 26-kb region characterized here was
acquired by strain D1 from strain JB2 and was located in the chromosome
of both organisms. Further studies to delineate the element's
boundaries and functional characteristics could provide new insights
into the mechanisms underlying evolution of bacterial genomes in
general and of catabolic pathways for anthropogenic pollutants in particular.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.10.4603-4609.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Cloning, Nucleotide Sequencing, and Functional
Analysis of a Novel, Mobile Cluster of Biodegradation Genes from
Pseudomonas aeruginosa Strain JB2
and
Madison,
Madison, Wisconsin
*
Corresponding author. Mailing address: Department of
Soil Science, University of Wisconsin
Madison, Madison, WI 53706-1299. Phone: (608) 262-9018. Fax: (608) 265-2595. E-mail:
wjhickey{at}facstaff.wisc.edu.
Present address: St. Andrew Presbyterian College, Laurenburg,
N.C.
Present address: Agracetus Inc., Middleton, Wis.
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