Novel tetracycline resistance determinant isolated from an environmental strain of Serratia marcescens

Stuart A Thompson, Elizabeth V. Maani, Angela H. Lindell, Catherine J. King, J. Vaun McArthur

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Resistances to tetracycline and mercury were identified in an environmental strain of Serratia marcescens isolated from a stream highly contaminated with heavy metals. As a step toward addressing the mechanisms of coselection of heavy metal and antibiotic resistances, the tetracycline resistance determinant was cloned in Escherichia coli. Within the cloned 13-kb segment, the tetracycline resistance locus was localized by deletion analysis and transposon mutagenesis. DNA sequence analysis of an 8.0-kb region revealed a novel gene [tetA(41)] that was predicted to encode a tetracycline efflux pump. Phylogenetic analysis showed that the TetA(41) protein was most closely related to the Tet(39) efflux protein of Acinetobacter spp. yet had less than 80% amino acid identity with known tetracycline efflux pumps. Adjacent to the tetA(41) gene was a divergently transcribed gene [tetR(41)] predicted to encode a tetracycline-responsive repressor protein. The tetA(41)-tetR(41) intergenic region contained putative operators for TetR(41) binding. The tetA(41) and tetR(41) promoters were analyzed using lacZ fusions, which showed that the expression of both the tetA(41) and tetR(41) genes exhibited TetR(41)-dependent regulation by subinhibitory concentrations of tetracycline. The apparent lack of plasmids in this S. marcescens strain, as well as the presence of metabolic genes adjacent to the tetracycline resistance locus, suggested that the genes were located on the S. marcescens chromosome and may have been acquired by transduction. The cloned Tet 41 determinant did not confer mercury resistance to E. coli, confirming that Tet 41 is a tetracycline-specific efflux pump rather than a multidrug transporter.

Original languageEnglish (US)
Pages (from-to)2199-2206
Number of pages8
JournalApplied and Environmental Microbiology
Volume73
Issue number7
DOIs
StatePublished - Apr 1 2007

Fingerprint

Tetracycline Resistance
Serratia marcescens
tetracycline
Tetracycline
gene
Genes
pump
transporters
Heavy Metals
Mercury
protein
genes
heavy metal
Escherichia coli
Repressor Proteins
mercury
Acinetobacter
Intergenic DNA
antibiotic resistance
Microbial Drug Resistance

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biotechnology
  • Microbiology

Cite this

Novel tetracycline resistance determinant isolated from an environmental strain of Serratia marcescens. / Thompson, Stuart A; Maani, Elizabeth V.; Lindell, Angela H.; King, Catherine J.; McArthur, J. Vaun.

In: Applied and Environmental Microbiology, Vol. 73, No. 7, 01.04.2007, p. 2199-2206.

Research output: Contribution to journalArticle

Thompson, Stuart A ; Maani, Elizabeth V. ; Lindell, Angela H. ; King, Catherine J. ; McArthur, J. Vaun. / Novel tetracycline resistance determinant isolated from an environmental strain of Serratia marcescens. In: Applied and Environmental Microbiology. 2007 ; Vol. 73, No. 7. pp. 2199-2206.
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abstract = "Resistances to tetracycline and mercury were identified in an environmental strain of Serratia marcescens isolated from a stream highly contaminated with heavy metals. As a step toward addressing the mechanisms of coselection of heavy metal and antibiotic resistances, the tetracycline resistance determinant was cloned in Escherichia coli. Within the cloned 13-kb segment, the tetracycline resistance locus was localized by deletion analysis and transposon mutagenesis. DNA sequence analysis of an 8.0-kb region revealed a novel gene [tetA(41)] that was predicted to encode a tetracycline efflux pump. Phylogenetic analysis showed that the TetA(41) protein was most closely related to the Tet(39) efflux protein of Acinetobacter spp. yet had less than 80{\%} amino acid identity with known tetracycline efflux pumps. Adjacent to the tetA(41) gene was a divergently transcribed gene [tetR(41)] predicted to encode a tetracycline-responsive repressor protein. The tetA(41)-tetR(41) intergenic region contained putative operators for TetR(41) binding. The tetA(41) and tetR(41) promoters were analyzed using lacZ fusions, which showed that the expression of both the tetA(41) and tetR(41) genes exhibited TetR(41)-dependent regulation by subinhibitory concentrations of tetracycline. The apparent lack of plasmids in this S. marcescens strain, as well as the presence of metabolic genes adjacent to the tetracycline resistance locus, suggested that the genes were located on the S. marcescens chromosome and may have been acquired by transduction. The cloned Tet 41 determinant did not confer mercury resistance to E. coli, confirming that Tet 41 is a tetracycline-specific efflux pump rather than a multidrug transporter.",
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