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Journal of Bacteriology, November 1999, p. 6650-6655, Vol. 181, No. 21
Unité des Agents Antibactériens,
Received 9 June 1999/Accepted 15 August 1999
Salmonella enterica subsp. enterica
serotype Enteritidis BM4361 and BM4362 were isolated from the same
patient. BM4361 was susceptible to aminoglycosides, whereas BM4362 was
resistant to tobramycin owing to synthesis of a
6'-N-acetyltransferase type I [AAC(6')-I]. Comparative
analysis of nucleotide sequences, pulsed-field gel electrophoresis
patterns, and Southern hybridizations indicated that the chromosomal
aac(6')-Iy genes for the enzyme in both strains were
identical and that BM4362 derived from BM4361 following a ca. 60-kb
deletion that occurred 1.5 kb upstream from the resistance gene.
Northern hybridizations showed that aac(6')-Iy was silent in BM4361 and highly expressed in BM4362 due to a transcriptional fusion. Primer extension mapping identified the transcriptional start
site for aac(6')-Iy in BM4362: 5 bp downstream from the promoter of the nmpC gene. Study of the distribution of
aac(6')-Iy by PCR and Southern hybridization with a
specific probe indicated that the gene, although not found in S. enterica subsp. arizonae, was specific for
Salmonella. In this bacterial genus, aac(6')-Iy was located downstream from a cluster of seven open reading frames analogous to an Escherichia coli locus that encodes enzymes
putatively involved in carbohydrate transport or metabolism. This
genomic environment suggests a role in the catabolism of a specific
sugar for AAC(6')-Iy in Salmonella.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Activation of the Cryptic aac(6')-Iy
Aminoglycoside Resistance Gene of Salmonella by a
Chromosomal Deletion Generating a Transcriptional Fusion
*
Corresponding author. Mailing address: Unité des
Agents Antibactériens, Institut Pasteur, 28, rue du Docteur Roux,
75724 Paris Cedex 15, France. Phone: (33) 1 45 68 83 20. Fax: (33) 1 45 68 83 20. Fax: (33) 1 45 68 83 19. E-mail:
pcourval{at}pasteur.fr.
Journal of Bacteriology, November 1999, p. 6650-6655, Vol. 181, No. 21
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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