scholarly journals A Newly Discovered Bacteroides Conjugative Transposon, CTnGERM1, Contains Genes Also Found in Gram-Positive Bacteria

2003 ◽  
Vol 69 (8) ◽  
pp. 4595-4603 ◽  
Author(s):  
Yanping Wang ◽  
Gui-Rong Wang ◽  
Aikiesha Shelby ◽  
Nadja B. Shoemaker ◽  
Abigail A. Salyers
Keyword(s):  
Amino Acid Sequence Identity ◽  
Efflux Pump ◽  
Antibiotic Resistance Genes ◽  
Pulsed Field Gel Electrophoresis ◽  
Erythromycin Resistance ◽  
Gram Positive ◽  
Conjugative Transposon ◽  
Gram Positive Bacteria ◽  
Sequence Identity ◽  
Predominant Type

ABSTRACT Results of a recent study of antibiotic resistance genes in human colonic Bacteroides strains suggested that gene transfer events between members of this genus are fairly common. The identification of Bacteroides isolates that carried an erythromycin resistance gene, ermG, whose DNA sequence was 99% identical to that of an ermG gene found previously only in gram-positive bacteria raised the further possibility that conjugal elements were moving into Bacteroides species from other genera. Six of seven ermG-containing Bacteroides strains tested were able to transfer ermG by conjugation. One of these strains was chosen for further investigation. Results of pulsed-field gel electrophoresis experiments showed that the conjugal element carrying ermG in this strain is an integrated element about 75 kb in size. Thus, the element appears to be a conjugative transposon (CTn) and was designated CTnGERM1. CTnGERM1 proved to be unrelated to the predominant type of CTn found in Bacteroides isolates—CTns of the CTnERL/CTnDOT family—which sometimes carry another type of erm gene, ermF. A 19-kbp segment of DNA from CTnGERM1 was cloned and sequenced. A 10-kbp portion of this segment hybridized not only to DNA from all the ermG-containing strains but also to DNA from strains that did not carry ermG. Thus, CTnGERM1 seems to be part of a family of CTns, some of which have acquired ermG. The percentage of G+C content of the ermG region was significantly lower than that of the chromosome of Bacteroides species—an indication that CTnGERM1 may have entered Bacteroides strains from some other bacterial genus. A survey of strains isolated before 1970 and after 1990 suggests that the CTnGERM1 type of CTn entered Bacteroides species relatively recently. One of the genes located upstream of ermG encoded a protein that had 85% amino acid sequence identity with a macrolide efflux pump, MefA, from Streptococcus pyogenes. Our having found >90% sequence identity of two upstream genes, including mefA, and the remnants of two transposon-carried genes downstream of ermG with genes found previously only in gram-positive bacteria raises the possibility that gram-positive bacteria could have been the origin of CTnGERM1.

scholarly journals A New Bacteroides Conjugative Transposon That Carries an ermB Gene

2003 ◽  
Vol 69 (11) ◽  
pp. 6455-6463 ◽  
Author(s):  
Anamika Gupta ◽  
Hera Vlamakis ◽  
Nadja Shoemaker ◽  
Abigail A. Salyers
Keyword(s):  
Antibiotic Resistance Genes ◽  
Open Reading Frames ◽  
Rrna Gene ◽  
Erythromycin Resistance ◽  
Gram Positive ◽  
Amino Acid Sequence Level ◽  
Conjugative Transposon ◽  
Pulsed Field ◽  
Gram Positive Bacteria ◽  
Ermb Gene

ABSTRACT The erythromycin resistance gene ermB has been found in a variety of gram-positive bacteria. This gene has also been found in Bacteroides species but only in six recently isolated strains; thus, the gene seems to have entered this genus only recently. One of the six Bacteroides ermB-containing isolates, WH207, could transfer ermB to Bacteroides thetaiotaomicron strain BT4001 by conjugation. WH207 was identified as a Bacteroides uniformis strain based on the sequence of its 16S rRNA gene. Results of pulsed-field gel electrophoresis experiments demonstrated that the transferring element was normally integrated into the Bacteroides chromosome. The element was estimated from pulsed-field gel data to be about 100 kb in size. Since the element appeared to be a conjugative transposon (CTn), it was designated CTnBST. CTnBST was able to mobilize coresident plasmids and the circular form of the mobilizable transposon NBU1 to Bacteroides and Escherichia coli recipients. A 13-kb segment that contained ermB was cloned and sequenced. Most of the open reading frames in this region had little similarity at the amino acid sequence level to any proteins in the sequence databases, but a 1,723-bp DNA segment that included a 950-bp segment downstream of ermB had a DNA sequence that was virtually identical to that of a segment of DNA found previously in a Clostridium perfringens strain. This finding, together with the finding that ermB is located on a CTn, supports the hypothesis that CTnBST could have entered Bacteroides from some other genus, possibly from gram-positive bacteria. Moreover, this finding supports the hypothesis that many transmissible antibiotic resistance genes in Bacteroides are carried on CTns.

scholarly journals Distribution of the ermG Gene among Bacterial Isolates from Porcine Intestinal Contents

2005 ◽  
Vol 71 (8) ◽  
pp. 4930-4934 ◽  
Author(s):  
Yanping Wang ◽  
Gui-Rong Wang ◽  
Nadja B. Shoemaker ◽  
Terence R. Whitehead ◽  
Abigail A. Salyers
Keyword(s):  
Insertion Sequence ◽  
Bacillus Sphaericus ◽  
Gram Positive ◽  
Sequence Element ◽  
Conjugative Transposon ◽  
Gram Positive Bacteria ◽  
First Finding ◽  
Intestinal Contents ◽  
Porcine Feces ◽  
Insertion Sequence Element

ABSTRACT The ermG gene was first found in the soil bacterium Bacillus sphaericus. More recently, it was found in several human intestinal Bacteroides species. We report here the first finding of ermG genes in gram-positive bacteria isolated from porcine feces and from under-barn manure pits used to store porcine wastes. The porcine ermG sequences were identical to the sequence of the B. sphaericus ermG gene except that six of the seven ermG-containing strains contained an insertion sequence element insertion in the C-terminal end of the gene. The porcine ermG genes were found in three different gram-positive genera, an indication that it is possible that the gene is being spread by horizontal gene transfer. A segment of a Bacteroides conjugative transposon that carries an ermG gene cross-hybridized with DNA from six of the seven porcine isolates, but the restriction patterns in the porcine strains were different from that of the Bacteroides conjugative transposon.

scholarly journals Medicinal Chemistry Updates on Bacterial Efflux Pump Modulators

2019 ◽  
Vol 25 (42) ◽  
pp. 6030-6069 ◽  
Author(s):  
Fernando Durães ◽  
Madalena Pinto ◽  
Emília Sousa
Keyword(s):  
Energy Source ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
The Other ◽  
Drug Uptake ◽  
Health Issues ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Efflux Pump Inhibitors

Antibiotic resistance is one of the most pressing health issues of our days. It can arise due to a multiplicity of factors, such as target modification, decrease in the drug uptake, changes in the metabolic pathways and activation of efflux pumps. The overexpression of efflux pumps is responsible for the extrusion of drugs, making antibiotic therapy fail, as the quantity of intracellular antibiotic is not enough to provide the desired therapeutic effect. Efflux pumps can be included in five families according to their composition, nature of substrates, energy source, and number of transmembrane spanning regions. The ABC superfamily is mainly found in Gram-positive bacteria, use ATP as an energy source, and only a limited number of ABC pumps confer multidrug resistance (MDR). On the other hand, the MFS family, most present in Gram-positive bacteria, and the RND family, characteristic of Gram-negative bacteria, are most associated with antibiotic resistance. A wide variety of inhibitors have been disclosed for both families, from either natural or synthetic sources, or even drugs that are currently in therapy for other diseases. The other two families are the SMR, which are the smallest drug efflux proteins known, and the MATE family, whose pumps can also resort to the sodium gradient as an energy source. In this review, it is intended to present a comprehensive review of the classes of efflux pump inhibitors from the various sources, highlighting their structure-activity relationships, which can be useful for medicinal chemists in the pursuit of novel efflux pump inhibitors.

scholarly journals Synthesis and Evaluation of a Chitosan Oligosaccharide-Streptomycin Conjugate against Pseudomonas aeruginosa Biofilms

Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 43 ◽  
Author(s):  
Ruilian Li ◽  
Xianghua Yuan ◽  
Jinhua Wei ◽  
Xiafei Zhang ◽  
Gong Cheng ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Water Solubility ◽  
Efflux Pump ◽  
Degree Of Polymerization ◽  
Water Soluble ◽  
Chitosan Oligosaccharide ◽  
Gram Positive ◽  
Pump System ◽  
Gram Positive Bacteria ◽  
Chitosan Oligosaccharides

Microbial biofilms are considerably more resistant to antibiotics than planktonic cells. It has been reported that chitosan coupling with the aminoglycoside antibiotic streptomycin dramatically disrupted biofilms of several Gram-positive bacteria. This finding suggested the application of the covalent conjugate of antimicrobial natural polysaccharides and antibiotics on anti-infection therapy. However, the underlying molecular mechanism of the chitosan-streptomycin conjugate (CS-Strep) remains unclear and the poor water-solubility of the conjugate might restrict its applications for anti-infection therapy. In this study, we conjugated streptomycin with water-soluble chitosan oligosaccharides (COS). Unlike CS-Strep, the COS-streptomycin conjugate (COS-Strep) barely affected biofilms of tested Gram-positive bacteria. However, COS-Strep efficiently eradicated established biofilms of the Gram-negative pathogen Pseudomonas aeruginosa. This activity of COS-Strep was influenced by the degree of polymerization of chitosan oligosaccharide. The increased susceptibility of P. aeruginosa biofilms to antibiotics after conjugating might be related to the following: Suppression of the activation of MexX-MexY drug efflux pump system induced by streptomycin treatment; and down-regulation of the biosynthesis of biofilm exopolysaccharides. Thus, this work indicated that covalently linking antibiotics to chitosan oligosaccharides was a possible approach for the development of antimicrobial drugs against biofilm-related infections.

scholarly journals Microarray-Based Detection of 90 Antibiotic Resistance Genes of Gram-Positive Bacteria

2005 ◽  
Vol 43 (5) ◽  
pp. 2291-2302 ◽  
Author(s):  
V. Perreten ◽  
L. Vorlet-Fawer ◽  
P. Slickers ◽  
R. Ehricht ◽  
P. Kuhnert ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Gram Positive ◽  
Gram Positive Bacteria

scholarly journals Integration and Excision of a Newly Discovered Bacteroides Conjugative Transposon, CTnBST

2006 ◽  
Vol 189 (3) ◽  
pp. 1072-1082 ◽  
Author(s):  
Neil A. Wesslund ◽  
Gui-Rong Wang ◽  
Bo Song ◽  
Nadja B. Shoemaker ◽  
Abigail A. Salyers
Keyword(s):  
Integration Site ◽  
Antibiotic Resistance Genes ◽  
Erythromycin Resistance ◽  
Crossover Region ◽  
Sequence Comparisons ◽  
Conjugative Transposon ◽  
Integrase Gene ◽  
Conjugative Transposons ◽  
Acid Protein ◽  
Amino Acid Protein

ABSTRACT Conjugative transposons (CTns) are major contributors to the spread of antibiotic resistance genes among Bacteroides species. CTnBST, a newly discovered Bacteroides conjugative transposon, carries an erythromycin resistance gene, ermB, and previously has been estimated to be about 100 kbp in size. We report here the locations and sequencing of both of its ends. We have also located and sequenced the gene that catalyzes the integration of CTnBST, intBST. The integrase gene encodes a 377-amino-acid protein that has the C-terminal R-K-H-R-H-Y motif that is characteristic of members of the tyrosine recombinase family of integrases. DNA sequence comparisons of the ends of CTnBST, the joined ends of the circular intermediate, and the preferred site into which the circular form of CTnBST had integrated revealed that the preferred integration site (attB1) contained an 18-bp sequence of identity to the crossover region, attBST, on CTnBST. Although this site was used in about one-half of the integration events, sequence analysis of these integration events revealed that both CTnBST and a miniature form of CTnBST (miniBST) integrated into a variety of other sites in the chromosome. All of the sites had two conserved regions, AATCTG and AAAT. These two regions flanked a 2-bp sequence, bp 10 and bp 11 of the 18-bp sequence, that varied in some of the different sites and sometimes in the attBST sequences. Our results suggest that CTnBST integrates site selectively and that the crossover appears to occur within a 12-bp region that contains the two regions of conserved sequences.

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