Cointegrase, a naturally occurring, truncated form of IS 21 transposase, catalyzes replicon fusion rather than simple insertion of IS 21 1 1Edited by J. Karn

Schmid, Stefan; Seitz, Thomas; Haas, Dieter

doi:10.1006/jmbi.1998.2041

Cited by 22 publications

(48 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Overlapping istAS by the last 8 nucleotides, the 753-bp istBS gene encodes a 250-amino-acid protein identical to IstBS in pSCFS3 with the exception of an R169G substitution. It has been proposed that the full-length 46-kDa IstA protein promotes simple transposition events via a "cut-and-paste" mechanism involving circularization of a single copy of IS21 to translocate DNA from the donor to the target site (50). This process is aided by the 30-kDa IstB helper protein (50).…”

Section: Resultsmentioning

confidence: 99%

Genetic Environment and Stability of cfr in Methicillin-Resistant Staphylococcus aureus CM05

Locke

Rahawi²,

LaMarre

et al. 2012

Antimicrob Agents Chemother

View full text Add to dashboard Cite

The Cfr methyltransferase confers resistance to many 50S ribosomal subunit-targeted antibiotics, including linezolid (LZD), via methylation of the 23S rRNA base A2503 in the peptidyl transferase center. Methicillin-resistant Staphylococcus aureus strain CM05 is the first clinical isolate documented to carry cfr. While cfr is typically plasmid borne, in CM05 it is located on the chromosome and is coexpressed with ermB as part of the mlr operon. Here we evaluated the chromosomal locus, association with mobile genetic elements, and stability of the cfr insertion region in CM05. The cfr-containing mlr operon is located within a 15.5-kb plasmid-like insertion into 23S rRNA allele 4. The region surrounding the cfr gene has a high degree of sequence similarity to the broad-host-range toxin/antitoxin multidrug resistance plasmid pSM19035, including a second ermB gene downstream of the mlr locus and istAS-istBS. Analysis of several individual CM05 colonies revealed two distinct populations for which LZD MICs were either 8 or 2 g/ml. In the LZD s colonies (designated CM05⌬), a recombination event involving the two ermB genes had occurred, resulting in the deletion of cfr and the 3= flanking region (cfr-istAS-istBS-ermB). The fitness advantage of CM05⌬ over CM05 (though not likely due to the cfr deletion itself) results in the predominance of CM05⌬ in the absence of selective pressure. Minicircles resulting from the ermB recombination event and the novel association of cfr with the pSM19035 plasmid system support the potential for the continued dissemination of cfr. R esistance to linezolid (LZD) was reported shortly after its introduction into the clinic and included both staphylococcal and enterococcal strains carrying G2576T mutations in one or more alleles of the domain V-encoding region of 23S rRNA genes (21, 57). These mutations perturb the conformation of the peptidyl transferase center, which is the target of oxazolidinones in the 50S ribosomal subunit (30,52,59). More recently, LZD resistance has been linked to additional mutations identified in the genes encoding 50S ribosomal proteins L3 and L4 (34, 58). Most problematic has been the identification of cfr, a horizontally transferable gene encoding a ribosomal methyltransferase that confers resistance to multiple classes of antibacterial agents targeting the peptidyl transferase center by posttranscriptional modification of the 23S rRNA (29). Recent studies have shown that Cfr methylates carbon 8 of nucleotide A2503 (20), thereby conferring a PhLOPS A phenotype characterized by decreased binding of phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A class antibiotics (29,37,56), as well as of 16-membered ring macrolides (55), to Cfr-methylated ribosomes. Of further concern is the low fitness cost associated with Cfr methylation (31) and the documentation of clinical cfr strains possessing co-occurring mutations in 23S rRNA (14) and ribosomal proteins L3 (36) and L4 (5). The need to maintain potency against strains with cfr and/or other LZ...

show abstract

Section: Resultsmentioning

confidence: 99%

Genetic Environment and Stability of cfr in Methicillin-Resistant Staphylococcus aureus CM05

Locke

Rahawi²,

LaMarre

et al. 2012

Antimicrob Agents Chemother

View full text Add to dashboard Cite

show abstract

“…Analysis of potential mobility pathways for cfr-IS21-558. For the IS21 family of insertion sequences, a double function of the istA gene product as a transposase or a cointegrase was described, depending on the use of alternative start codons that may enlarge the IstA protein by 3 to 11 aa (1,17). For the pSCFS6-associated IS21-558 elements, such an alternative start codon, GTG, was also detected 12 bp upstream of the ATG start codon.…”

Section: Resultsmentioning

confidence: 99%

IS 21-558 Insertion Sequences Are Involved in the Mobility of the Multiresistance Gene cfr

Kehrenberg

Aarestrup

Schwarz

2007

Antimicrob Agents Chemother

112

View full text Add to dashboard Cite

During a study of florfenicol-resistant porcine staphylococci from Denmark, the genes cfr and fexA were detected in the chromosomal DNA or on plasmids of Staphylococcus hyicus, Staphylococcus warneri, and Staphylococcus simulans. A novel variant of the phenicol resistance transposon Tn558 was detected on the ca. 43-kb plasmid pSCFS6 in S. warneri and S. simulans isolates. Sequence analysis of a 22,010-bp segment revealed that the new Tn558 variant harbored an additional resistance gene region integrated into the tnpC reading frame. This resistance gene region consisted of the clindamycin exporter gene lsa(B) and the gene cfr for combined resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A antibiotics bracketed by IS21-558 insertion sequences orientated in the same direction. A 6-bp target site duplication was detected at the integration site within tnpC. Transpositionally active forms of the IS21-558 element, known as minicircles, were detected by PCR and suggest that this insertion sequence is involved in the mobility of the multiresistance gene cfr. Based on the knowledge of the transposition pathways of IS21-like insertion sequences and the sequence features detected, the resistance gene region of plasmid pSCFS6 is believed to have developed via IS21-558-mediated cointegrate formation. The data obtained in this study identified the multiresistance gene cfr not only in three novel host species but also in a novel genetic context whose further analysis suggested that insertion sequences of the type IS21-558 are likely to be involved in the dissemination of cfr.The gene cfr was initially discovered in a bovine Staphylococcus sciuri isolate during a florfenicol surveillance study of staphylococci from animals (19). In 2005, it was shown that the Cfr protein represents a methyltransferase which modifies the 23S rRNA (6). Detailed footprint analysis and mass spectrometric studies showed that the Cfr enzyme adds an additional methyl group at position A2503 (6). This Cfr-mediated modification affected not only the binding of phenicols but also that of members of another four different drug classes to the bacterial ribosome. The corresponding multidrug resistance phenotype was characterized by elevated MICs to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A (PhLOPS A ) antibiotics, all of which are important antimicrobial agents for the treatment of bacterial infections in humans and/or animals (7). The PhLOPS A phenotype was expressed not only in Staphylococcus aureus but also in Escherichia coli carrying the gene cfr (7).So far, the gene cfr has been detected in six staphylococcal isolates of animal origin, located either on the 17.1-kb plasmid type pSCFS1 or on the 35.7-kb plasmid type pSCFS3 (4). Recently, cfr has also been detected in a methicillin-resistant S. aureus isolate of human origin (8a). In the completely sequenced plasmid pSCFS1, the gene cfr was located in close proximity to other antibiotic resistance genes, such as lsa (B), erm(33)...

show abstract

“…strain KHP41 (33). Two ORFs, ORF28 (24327 to 25175) and ORF29 (25159 to 25416), had homology to the IstB and IstA proteins from Ralstonia eutropha, respectively (51). In plasmids carrying the insertion sequence IS21, istAB are usually transcribed as part of an operon (51).…”

Section: Analyses Of Orfsmentioning

confidence: 99%

Complete Nucleotide Sequence and Organization of the Atrazine Catabolic Plasmid pADP-1 from Pseudomonas sp . Strain ADP

et al. 2001

View full text Add to dashboard Cite

The complete 108,845-nucleotide sequence of catabolic plasmid pADP-1 from Pseudomonas sp. strain ADP was determined. Plasmid pADP-1 was previously shown to encode AtzA, AtzB, and AtzC, which catalyze the sequential hydrolytic removal of s-triazine ring substituents from the herbicide atrazine to yield cyanuric acid. Computational analyses indicated that pADP-1 encodes 104 putative open reading frames (ORFs), which are predicted to function in catabolism, transposition, and plasmid maintenance, transfer, and replication. Regions encoding transfer and replication functions of pADP-1 had 80 to 100% amino acid sequence identity to pR751, an IncP␤ plasmid previously isolated from Enterobacter aerogenes. pADP-1 was shown to contain a functional mercury resistance operon with 99% identity to Tn5053. Complete copies of transposases with 99% amino acid sequence identity to TnpA from IS1071 and TnpA from Pseudomonas pseudoalcaligenes were identified and flank each of the atzA, atzB, and atzC genes, forming structures resembling nested catabolic transposons. Functional analyses identified three new catabolic genes, atzD, atzE, and atzF, which participate in atrazine catabolism. Crude extracts from Escherichia coli expressing AtzD hydrolyzed cyanuric acid to biuret. AtzD showed 58% amino acid sequence identity to TrzD, a cyanuric acid amidohydrolase, from Pseudomonas sp. strain NRRLB-12227. Two other genes encoding the further catabolism of cyanuric acid, atzE and atzF, reside in a contiguous cluster adjacent to a potential LysR-type transcriptional regulator. E. coli strains bearing atzE and atzF were shown to encode a biuret hydrolase and allophanate hydrolase, respectively. atzDEF are cotranscribed. AtzE and AtzF are members of a common amidase protein family. These data reveal the complete structure of a catabolic plasmid and show that the atrazine catabolic genes are dispersed on three disparate regions of the plasmid. These results begin to provide insight into how plasmids are structured, and thus evolve, to encode the catabolism of compounds recently added to the biosphere.

show abstract

Cointegrase, a naturally occurring, truncated form of IS 21 transposase, catalyzes replicon fusion rather than simple insertion of IS 21 1 1Edited by J. Karn

Cited by 22 publications

References 38 publications

Genetic Environment and Stability of cfr in Methicillin-Resistant Staphylococcus aureus CM05

Genetic Environment and Stability of cfr in Methicillin-Resistant Staphylococcus aureus CM05

IS 21-558 Insertion Sequences Are Involved in the Mobility of the Multiresistance Gene cfr

Complete Nucleotide Sequence and Organization of the Atrazine Catabolic Plasmid pADP-1 from Pseudomonas sp . Strain ADP

Contact Info

Product

Resources

About