scholarly journals The mercury resistance (mer) operon in a marine gliding flavobacterium,Tenacibaculum discolor9A5

2012 ◽  
Vol 83 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Rachel C. Allen ◽  
Yen-Kuei Tu ◽  
Michael J. Nevarez ◽  
Alexander S. Bobbs ◽  
Joseph W. Friesen ◽  
...  
Keyword(s):  
Mercury Resistance ◽  
Mer Operon

Deletion mutant analysis of the Staphylococcus aureus plasmid pI258 mercury-resistance determinant

1991 ◽  
Vol 37 (8) ◽  
pp. 624-631 ◽  
Author(s):  
Kenneth Babich ◽  
Mike Engle ◽  
Jeffery S. Skinner ◽  
Richard A. Laddaga
Keyword(s):  
Staphylococcus Aureus ◽  
Ion Transport ◽  
Copy Number ◽  
Deletion Mutant ◽  
Resistance Determinant ◽  
Mercury Resistance ◽  
Mutant Analysis ◽  
Mer Operon ◽  
Copy Number Plasmid ◽  
High Copy Number Plasmid

Deletion mutant analysis of the mercury-resistant determinant (mer operon) from the Staphylococcus aureus plasmid pI258 was used to verify the location of the merA and merB genes and to show the existence of mercuric ion transport gene(s). ORF5 was confirmed to be a transport gene and has an amino acid product sequence homologous to the merT gene products from several gram-negative bacteria and a Bacillus species. Deletion analysis established that inactivation of merA on a broad-spectrum mer resistance determinant resulted in a mercury-hypersensitive phenotype. Gene dosage had no apparent effect on the level of resistance conferred by the intact mer operon or on the expression of an inducible phenotype, except that when the intact pI258 mer operon was on a high copy number plasmid, uninduced cells possessed a volatilization rate that was at most only 3.5-fold less than that observed for induced cells. There was no need for mercury ion transport proteins for full resistance when the mer operon was expressed in a high copy number plasmid. Key words: mercury resistance, Staphylococcus aureus plasmid.

scholarly journals Transposon Tn21, Flagship of the Floating Genome

1999 ◽  
Vol 63 (3) ◽  
pp. 507-522 ◽  
Author(s):  
Cynthia A. Liebert ◽  
Ruth M. Hall ◽  
Anne O. Summers
Keyword(s):  
Antibiotic Resistance ◽  
Antibiotic Resistance Genes ◽  
Toxic Metal ◽  
Gene Cassette ◽  
Mercury Resistance ◽  
Mobile Dna ◽  
Specific System ◽  
Mer Operon ◽  
Usage Analysis ◽  
A Site

SUMMARY The transposon Tn21 and a group of closely related transposons (the Tn21 family) are involved in the global dissemination of antibiotic resistance determinants in gram-negative facultative bacteria. The molecular basis for their involvement is carriage by the Tn21 family of a mobile DNA element (the integron) encoding a site-specific system for the acquisition of multiple antibiotic resistance genes. The paradigm example, Tn21, also carries genes for its own transposition and a mercury resistance (mer) operon. We have compiled the entire 19,671-bp sequence of Tn21 and assessed the possible origins and functions of the genes it contains. Our assessment adds molecular detail to previous models of the evolution of Tn21 and is consistent with the insertion of the integron In2 into an ancestral Tn501-like mer transposon. Codon usage analysis indicates distinct host origins for the ancestral mer operon, the integron, and the gene cassette and two insertion sequences which lie within the integron. The sole gene of unknown function in the integron, orf5, resembles a puromycin-modifying enzyme from an antibiotic producing bacterium. A possible seventh gene in the mer operon (merE), perhaps with a role in Hg(II) transport, lies in the junction between the integron and the mer operon. Analysis of the region interrupted by insertion of the integron suggests that the putative transposition regulator, tnpM, is the C-terminal vestige of a tyrosine kinase sensor present in the ancestral mer transposon. The extensive dissemination of the Tn21 family may have resulted from the fortuitous association of a genetic element for accumulating multiple antibiotic resistances (the integron) with one conferring resistance to a toxic metal at a time when clinical, agricultural, and industrial practices were rapidly increasing the exposure to both types of selective agents. The compendium offered here will provide a reference point for ongoing observations of related elements in multiply resistant strains emerging worldwide.

scholarly journals Distribution, diversity and evolution of the bacterial mercury resistance (mer) operon

1997 ◽  
Vol 19 (4) ◽  
pp. 239-262 ◽  
Author(s):  
A. Mark Osborn ◽  
Kenneth D. Bruce ◽  
Peter Strike ◽  
Donald A. Ritchie
Keyword(s):  
Mercury Resistance ◽  
Mer Operon

scholarly journals Nearly Identical Plasmids Encoding VIM-1 and Mercury Resistance in Enterobacteriaceae from North-Eastern Germany

2021 ◽  
Vol 9 (7) ◽  
pp. 1345
Author(s):  
Stefan E. Heiden ◽  
Katharina Sydow ◽  
Stephan Schaefer ◽  
Ingo Klempien ◽  
Veronika Balau ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Bacterial Species ◽  
Genomic Analysis ◽  
Public Health Problem ◽  
Multidrug Resistant ◽  
Mercury Resistance ◽  
Major Public Health Problem ◽  
Eastern Germany ◽  
North Eastern ◽  
Resistance Plasmids

The emergence of carbapenemase-producing Enterobacteriaceae limits therapeutic options and presents a major public health problem. Resistances to carbapenems are mostly conveyed by metallo-beta-lactamases (MBL) including VIM, which are often encoded on resistance plasmids. We characterized four VIM-positive isolates that were obtained as part of a routine diagnostic screening from two laboratories in north-eastern Germany between June and August 2020. Whole-genome sequencing was performed to address (a) phylogenetic properties, (b) plasmid content, and (c) resistance gene carriage. In addition, we performed phenotypic antibiotic and mercury resistance analyses. The genomic analysis revealed three different bacterial species including C. freundii, E. coli and K. oxytoca with four different sequence types. All isolates were geno- and phenotypically multidrug-resistant (MDR) and the phenotypic profile was explained by the underlying resistance gene content. Three isolates of four carried nearly identical VIM-1-resistance plasmids, which in addition encoded a mercury resistance operon and showed some similarity to two publicly available plasmid sequences from sources other than the two laboratories above. Our results highlight the circulation of a nearly identical IncN-type VIM-1-resistance plasmid in different Enterobacteriaceae in north-eastern Germany.

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