β-Lactamase Gene Expression in a Penicillin-Resistant
            <i>Bacillus anthracis</i>
            Strain

Chen, Yahua; Tenover, Fred C.; Koehler, Theresa M.

doi:10.1128/aac.48.12.4873-4877.2004

Cited by 89 publications

(71 citation statements)

References 30 publications

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“…Since a distinguishing feature of B. anthracis is its susceptibility to penicillin (Turnbull, 1999), it is possible that one (or more) of these TCSs contributes to penicillin resistance in B. cereus and B. thuringiensis and that it is indeed non-functional in B. anthracis. Recent work has shown that penicillin-susceptible B. anthracis strains contain silent b-lactamase genes, while these genes are active in penicillin-resistant members of the B. cereus group (Chen et al, 2003(Chen et al, , 2004. Given these data, it is plausible that one or more of the non-truncated TCSs in B. cereus and B. thuringiensis provide a route for activation of the blactamase genes, while their truncated orthologues in B. anthracis are unable to activate these genes.…”

Section: Differences In Tcss Within the B Cereus Groupmentioning

confidence: 99%

Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

et al. 2006

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Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and its cognate response regulator (RR). With the use of in silico techniques, a complete set of HKs and RRs was recovered from eight completely sequenced B. cereus group genomes. By applying a bidirectional best-hits method combined with gene neighbourhood analysis, a footprint of these proteins was made. Around 40 HK-RR gene pairs were detected in each member of the B. cereus group. In addition, each member contained many HK and RR genes not encoded in pairs (‘orphans’). Classification of HKs and RRs based on their enzymic domains together with the analysis of two neighbour-joining trees of these domains revealed putative interaction partners for most of the ‘orphans’. Putative biological functions, including involvement in virulence and host–microbe interactions, were predicted for the B. cereus group HKs and RRs by comparing them with those of B. subtilis and other micro-organisms. Remarkably, B. anthracis appeared to lack specific HKs and RRs and was found to contain many truncated, putatively non-functional, HK and RR genes. It is hypothesized that specialization of B. anthracis as a pathogen could have reduced the range of environmental stimuli to which it is exposed. This may have rendered some of its TCSs obsolete, ultimately resulting in the deletion of some HK and RR genes.

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Section: Differences In Tcss Within the B Cereus Groupmentioning

confidence: 99%

Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

et al. 2006

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“…The protocols used for constructing single and double knockout mutants were as previously published [28][29][30][31]. The primer sequences are available upon request.…”

Section: B Anthracis Strain Constructionsmentioning

confidence: 99%

Deletion of dnaN1 generates a mutator phenotype in Bacillus anthracis

Yang

Miller

2008

DNA Repair

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The dnaN gene in eubacteria is an essential gene that encodes the β subunit of replicative DNA polymerase. Nearly all eubacterial genomes sequenced to date predict a single copy of the dnaN gene in a well-conserved neighboring gene context. However, 19 genomes out of 348 scanned, including Bacillus anthracis, Bacillus cereus, Bacillus thuringiensis, and Bacillus weihenstephanensis, predict more than one dnaN gene. In most cases, these genomes appear to maintain a copy of the dnaN homolog in its usual neighboring gene context (designated as dnaN1) in addition to a second copy (designated as dnaN2) in an entirely different gene context. We used B. anthracis as our model system to investigate the role of these DnaNs. We constructed a single knockout mutant of dnaN1 and of dnaN2; however, we could not make a viable double knockout mutant of dnaN1 and dnaN2. The dnaN1 knockout mutant displays a markedly reduced colony size. It also displays a significantly increased mutation rate, which is similar to that of a mismatch repair deficient strain and to a strain deficient both in dnaN1 and mismatch repair. The dnaN2 knockout mutant, however, has a similar growth rate and a comparable mutation rate to that of the wild type. This is the first study demonstrating the existence of two functional DnaN homologs in the B. anthracis genome, with DnaN1 appearing to be more crucial than DnaN2. Our results also suggest the direct involvement of DnaN1 in the DNA mismatch repair process, which is consistent with previous findings.

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“…However, its ability to develop resistance to antimicrobial agents is currently a major concern. For example, although penicillin is considered the treatment of choice for all forms of anthrax, many penicillin-resistant strains and treatment failures have been reported in the literature [5][6][7] . Reports of B anthracis resistance to ciprofloxacin and other antibiotics have likewise appeared [8][9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

Daptomycin exerts rapid bactericidal activity against Bacillus anthracis without disrupting membrane integrity

Xing

Wang

Dai³

et al. 2013

Acta Pharmacol Sin

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Aim: To examine whether the novel cyclic lipopeptide antibiotic daptomycin could be used to treat anthrax and to study the mechanisms underlying its bactericidal action against Bacillus anthracis. Methods: Spore-forming B anthracis AP422 was tested. MIC values of antibiotics were determined. Cell membrane potential was measured using flow cytometric assays with membrane potential-sensitive fluorescent dyes. Cell membrane integrity was detected using To-Pro-3 iodide staining and transmission electron microscopy. K + efflux and Na + influx were measured using the fluorescent probes PBFI and SBFI-AM, respectively. Results: Daptomycin exhibited rapid bactericidal activity against vegetative B anthracis with a MIC value of 0.78 μg/mL, which was comparable to those of ciprofloxacin and penicillin G. Furthermore, daptomycin prevented the germinated spores from growing into vegetative bacteria. Daptomycin concentration-dependently dissipated the membrane potential of B anthracis and caused K + efflux and Na + influx without disrupting membrane integrity. In contrast, both ciprofloxacin and penicillin G did not change the membrane potential of vegetative bacteria or spores. Penicillin G disrupted membrane integrity of B anthracis, whereas ciprofloxacin had no such effect. Conclusion: Daptomycin exerts rapid bactericidal action against B anthracis via reducing membrane potential without disrupting membrane integrity. This antibiotic can be used as an alternate therapy for B anthracis infections.

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β-Lactamase Gene Expression in a Penicillin-Resistant Bacillus anthracis Strain

Cited by 89 publications

References 30 publications

Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

Deletion of dnaN1 generates a mutator phenotype in Bacillus anthracis

Daptomycin exerts rapid bactericidal activity against Bacillus anthracis without disrupting membrane integrity

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