scholarly journals Distribution, Diversity, and Potential Mobility of Extrachromosomal Elements Related to the Bacillus anthracis pXO1 and pXO2 Virulence Plasmids

2009 ◽  
Vol 75 (10) ◽  
pp. 3016-3028 ◽  
Author(s):  
Xiaomin Hu ◽  
G�raldine Van der Auwera ◽  
Sophie Timmery ◽  
Lei Zhu ◽  
Jacques Mahillon
Keyword(s):  
Bacillus Anthracis ◽  
Environmental Samples ◽  
Virulence Genes ◽  
Sensu Stricto ◽  
Large Plasmid ◽  
Virulence Plasmids ◽  
Extrachromosomal Elements ◽  
Transfer Genes ◽  
Potential Mobility ◽  
Transfer Potential

ABSTRACT The presence of a pXO1- and/or pXO2-like plasmid(s) in clinical isolates of Bacillus cereus sensu stricto and in strains of the biopesticide Bacillus thuringiensis has been reported recently, and the pXO2-like plasmid pBT9727 and another pXO2-like plasmid, pAW63, were found to be conjugative. In this study, a total of 1,000 B. cereus group isolates were analyzed for the presence of pXO1- and pXO2-like replicons and for the presence of pXO2-related conjugative modules. pXO1- and pXO2-like replicons were present in ca. 6.6% and 7.7% of random environmental samples, respectively, and ca. 1.54% of the strains were positive for pXO2-like transfer module genes. Only the strains harboring a pXO2-like replicon also contained the corresponding transfer genes. For the strains which contained a pXO1- and/or pXO2-like replicon(s), a large plasmid(s) whose size was similar to that of pXO1-like and/or pXO2-like plasmids was also observed, but none of these isolates were found to carry the Bacillus anthracis toxin or capsule virulence genes. Furthermore, 17 of 22 pXO2-like plasmids containing the transfer modules were able to self-transfer and to mobilize small plasmids. No pXO1- or pXO2-like plasmid lacking the cognate transfer modules has been found to have transfer potential. In the strains possessing the putative pXO2-like conjugative apparatus, variations in the presence of the group II introns B.th.I.1 and B.th.I.2 were observed, suggesting that there is important flexibility in the conjugation modules and their regulation. There was no consistent correlation between a pXO2-like repA dendrogram and the presence of the tra region or between a virB4 dendrogram and transfer ability. Discrepancies between pXO2-like repA and virB4 dendrograms were also observed, indicating that the evolution of pXO2 is an active process.

scholarly journals A Unique GTP-Dependent Sporulation Sensor Histidine Kinase in Bacillus anthracis

2008 ◽  
Vol 191 (3) ◽  
pp. 687-692 ◽  
Author(s):  
Francesca Scaramozzino ◽  
Andrea White ◽  
Marta Perego ◽  
James A. Hoch
Keyword(s):  
Bacillus Anthracis ◽  
Histidine Kinase ◽  
Catalytic Domain ◽  
Coiled Coil ◽  
Reverse Reaction ◽  
Forward Reaction ◽  
Critical Signal ◽  
Sensor Histidine Kinase ◽  
Virulence Plasmids ◽  
Kinase Catalytic Domain

ABSTRACT The Bacillus anthracis BA2291 gene codes for a sensor histidine kinase involved in the induction of sporulation. Genes for orthologs of the sensor domain of the BA2291 kinase exist in virulence plasmids in this organism, and these proteins, when expressed, inhibit sporulation by converting BA2291 to an apparent phosphatase of the sporulation phosphorelay. Evidence suggests that the sensor domains inhibit BA2291 by titrating its activating signal ligand. Studies with purified BA2291 revealed that this kinase is uniquely specific for GTP in the forward reaction and GDP in the reverse reaction. The G1 motif of BA2291 is highly modified from ATP-specific histidine kinases, and modeling this motif in the structure of the kinase catalytic domain suggested how guanine binds to the region. A mutation in the putative coiled-coil linker between the sensor domain and the catalytic domains was found to decrease the rate of the forward autophosphorylation reaction and not affect the reverse reaction from phosphorylated Spo0F. The results suggest that the activating ligand for BA2291 is a critical signal for sporulation and in a limited concentration in the cell. Decreasing the response to it either by slowing the forward reaction through mutation or by titration of the ligand by expressing the plasmid-encoded sensor domains switches BA2291 from an inducer to an inhibitor of the phosphorelay and sporulation.

scholarly journals Occurrence of virulent multidrug-resistantEnterococcus faecalisandEnterococcus faeciumin the pigs, farmers and farm environments in Malaysia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5353 ◽  
Author(s):  
Shiang Chiet Tan ◽  
Chun Wie Chong ◽  
Cindy Shuan Ju Teh ◽  
Peck Toung Ooi ◽  
Kwai Lin Thong
Keyword(s):  
Polymerase Chain Reaction ◽  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Environmental Samples ◽  
Virulence Genes ◽  
Multidrug Resistant ◽  
Peninsular Malaysia ◽  
Chain Reaction ◽  
Swine Farms ◽  
Polymerase Chain

BackgroundEnterococcus faecalisandEnterococcus faeciumare ubiquitous opportunistic pathogens found in the guts of humans and farmed animals. This study aimed to determine the occurrence, antimicrobial resistance, virulence, biofilm-forming ability and genotypes ofE. faecalisandE. faeciumfrom swine farms. Correlations between the genotypes, virulotypes, antibiotic resistance, and the environmental factors such as locality of farms and farm hygiene practice were explored.MethodsE. faecalisandE. faeciumstrains were isolated from the oral, rectal and fecal samples of 140 pigs; nasal, urine and fecal samples of 34 farmers working in the farms and 42 environmental samples collected from seven swine farms located in Peninsular Malaysia. Antibiotic susceptibility test was performed using the disk diffusion method, and the antibiotic resistance and virulence genes were detected by Polymerase Chain Reaction. Repetitive Extragenic Palindromic-Polymerase Chain Reaction and Pulsed-Field Gel Electrophoresis were performed to determine the clonality of the strains. Crosstab/Chi-square test and DistLM statistical analyses methods were used to determine the correlations between the genotypes, virulence factors, antibiotic resistance, and the environmental factors.ResultsA total of 211E. faecalisand 42E. faeciumwere recovered from 140 pigs, 34 farmers and 42 environmental samples collected from seven swine farms in Peninsular Malaysia. Ninety-eight percent of the strains were multidrug-resistant (resistant to chloramphenicol, tetracycline, ciprofloxacin and erythromycin). Fifty-two percent of the strains formed biofilms. Virulence genesefa, asaI, gelE,esp,cylandacegenes were detected. Virulence genesefaandasaI were most prevalent inE. faecalis(90%) andE. faecium(43%), respectively. Cluster analyses based on REP-PCR and PFGE showed the strains were genetically diverse. Overall, the strains isolated from pigs and farmers were distinct, except for three highly similar strains found in pigs and farmers. The strains were regional- and host-specific.DiscussionThis study revealed alarming high frequencies of multidrug-resistant enterococci in pigs and swine farmers. The presence of resistance and virulence genes and the ability to form biofilm further enhance the persistence and pathogenicity of the strains. Although the overall clonality of the strains were regionals and host-specific, strains with high similarity were found in different hosts. This study reiterates a need of a more stringent regulation to ensure the proper use of antibiotics in swine husbandry to reduce the wide spread of multidrug-resistant strains.

Spiroplasmas as Biological Control Agents of Insect Pests

1995 ◽  
Author(s):  
Kevin Hackett ◽  
Shlomo Rottem ◽  
David L. Williamson ◽  
Meir Klein
Keyword(s):  
Leptinotarsa Decemlineata ◽  
Virulence Genes ◽  
Insect Pests ◽  
The United States ◽  
Origin Of Replication ◽  
Shuttle Vectors ◽  
Large Unilamellar Vesicles ◽  
Extrachromosomal Elements ◽  
Genetically Engineer ◽  
Large Clusters

Toward development of spiroplasmas as novel toxin-delivery systems for biocontrol of beetle pests in the United States (Leptinotarsa decemlineata) and Israel (Maladera matrida), media for cultivating beetle-associated spiroplasmas were improved and surveys of these spiroplasmas were conducted to provide transformable strains. Extensive surveys of spiroplasmas yielded promising extrachromosomal elements for vector constructs. One, plasmid pCT-1, was cloned, characterized, and used as a source of spiroplasma origin of replication in our shuttle vectors. The fibrillin gene was isolated and sequenced and its strong promoter was also used in the constructs. Means for transforming these vectors into spiroplasmas were developed and optimized, with electroporation found to be suitable for most applications. Development and optimization of means for using large unilamellar vesicles (LUVs) in spiroplasma transformation represents a breakthrough that should facilitate insertion of large clusters of virulence genes. With completion of the vector, we should thus be poised to genetically engineer spiroplasmas with genes that will express toxins lethal to our target beetles, thus providing an effective and inexpensive alternative to conventional means of beetle control.

scholarly journals vacB, a novel chromosomal gene required for expression of virulence genes on the large plasmid of Shigella flexneri.

1992 ◽  
Vol 174 (20) ◽  
pp. 6359-6367 ◽  
Author(s):  
T Tobe ◽  
C Sasakawa ◽  
N Okada ◽  
Y Honma ◽  
M Yoshikawa
Keyword(s):  
Virulence Genes ◽  
Shigella Flexneri ◽  
Large Plasmid ◽  
Chromosomal Gene

Unexpected conservation and global transmission of agrobacterial virulence plasmids

Science ◽  
2020 ◽  
Vol 368 (6495) ◽  
pp. eaba5256 ◽  
Author(s):  
Alexandra J. Weisberg ◽  
Edward W. Davis ◽  
Javier Tabima ◽  
Michael S. Belcher ◽  
Marilyn Miller ◽  
...  
Keyword(s):  
Host Species ◽  
Evolutionary History ◽  
Virulence Plasmids ◽  
Ri Plasmid ◽  
Accelerated Evolution ◽  
Transfer Genes ◽  
Global Spread

The accelerated evolution and spread of pathogens are threats to host species. Agrobacteria require an oncogenic Ti or Ri plasmid to transfer genes into plants and cause disease. We developed a strategy to characterize virulence plasmids and applied it to analyze hundreds of strains collected between 1927 and 2017, on six continents and from more than 50 host species. In consideration of prior evidence for prolific recombination, it was surprising that oncogenic plasmids are descended from a few conserved lineages. Characterization of a hierarchy of features that promote or constrain plasticity allowed inference of the evolutionary history across the plasmid lineages. We uncovered epidemiological patterns that highlight the importance of plasmid transmission in pathogen diversification as well as in long-term persistence and the global spread of disease.

scholarly journals Differential Proteomic Analysis of the Bacillus anthracis Secretome: Distinct Plasmid and Chromosome CO2-Dependent Cross Talk Mechanisms Modulate Extracellular Proteolytic Activities

2006 ◽  
Vol 188 (10) ◽  
pp. 3551-3571 ◽  
Author(s):  
Theodor Chitlaru ◽  
Orit Gat ◽  
Yael Gozlan ◽  
Naomi Ariel ◽  
Avigdor Shafferman
Keyword(s):  
Bacillus Anthracis ◽  
Expression Patterns ◽  
Dependent Manner ◽  
Gene Products ◽  
Virulence Determinants ◽  
Virulence Plasmids ◽  
Proteomic Approach ◽  
Enhanced Expression ◽  
Proteolytic Activities ◽  
Protein Relative Abundance

ABSTRACT The secretomes of a virulent Bacillus anthracis strain and of avirulent strains (cured of the virulence plasmids pXO1 and pXO2), cultured in rich and minimal media, were studied by a comparative proteomic approach. More than 400 protein spots, representing the products of 64 genes, were identified, and a unique pattern of protein relative abundance with respect to the presence of the virulence plasmids was revealed. In minimal medium under high CO2 tension, conditions considered to simulate those encountered in the host, the presence of the plasmids leads to enhanced expression of 12 chromosome-carried genes (10 of which could not be detected in the absence of the plasmids) in addition to expression of 5 pXO1-encoded proteins. Furthermore, under these conditions, the presence of the pXO1 and pXO2 plasmids leads to the repression of 14 chromosomal genes. On the other hand, in minimal aerobic medium not supplemented with CO2, the virulent and avirulent B. anthracis strains manifest very similar protein signatures, and most strikingly, two proteins (the metalloproteases InhA1 and NprB, orthologs of gene products attributed to the Bacillus cereus group PlcR regulon) represent over 90% of the total secretome. Interestingly, of the 64 identified gene products, at least 31 harbor features characteristic of virulence determinants (such as toxins, proteases, nucleotidases, sulfatases, transporters, and detoxification factors), 22 of which are differentially regulated in a plasmid-dependent manner. The nature and the expression patterns of proteins in the various secretomes suggest that distinct CO2-responsive chromosome- and plasmid-encoded regulatory factors modulate the secretion of potential novel virulence factors, most of which are associated with extracellular proteolytic activities.

scholarly journals atxA Controls Bacillus anthracis Capsule Synthesis via acpA and a Newly Discovered Regulator, acpB

2004 ◽  
Vol 186 (2) ◽  
pp. 307-315 ◽  
Author(s):  
Melissa Drysdale ◽  
Agathe Bourgogne ◽  
Susan G. Hilsenbeck ◽  
Theresa M. Koehler
Keyword(s):  
Gene Expression ◽  
Bacillus Anthracis ◽  
Gene Transcription ◽  
Double Mutant ◽  
Regulatory Proteins ◽  
Toxin Gene ◽  
Virulence Plasmid ◽  
Predicted Amino Acid Sequence ◽  
Null Mutant ◽  
Virulence Plasmids

ABSTRACT Two regulatory genes, acpA and atxA, have been reported to control expression of the Bacillus anthracis capsule biosynthesis operon capBCAD. The atxA gene is located on the virulence plasmid pXO1, while pXO2 carries acpA and the cap genes. acpA has been viewed as the major regulator of the cap operon because it is essential for capsule gene expression in a pXO1− pXO2+ strain. atxA is essential for toxin gene transcription but has also been implicated in control of the cap genes. The molecular functions of the regulatory proteins are unknown. We examined cap gene expression in a genetically complete pXO1+ pXO2+ strain. Our results indicate that another pXO2 gene, acpB (previously called pXO2-53; accession no. NC002146.1 :49418-50866), has a role in cap expression. The predicted amino acid sequence of AcpB is 62% similar to that of AcpA and 50% similar to that of AtxA. Assessment of cap gene transcription revealed that cap expression was not affected in a pXO1+ pXO2+ acpB-null mutant and was slightly reduced in an isogenic acpA mutant. However, cap gene expression was abolished in an acpA acpB double mutant. Microscopic examination of capsule synthesis by the mutants corroborated these findings. acpA and acpB expression is controlled by atxA; capsule synthesis and transcription of acpA and acpB were markedly reduced in an atxA mutant. The data suggest that, in a strain containing both virulence plasmids, atxA is the major regulator of capsule synthesis and controls capBCAD expression indirectly, via positive regulation of acpA and acpB.

scholarly journals Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

2006 ◽  
Vol 188 (16) ◽  
pp. 5975-5983 ◽  
Author(s):  
Timothy J. Johnson ◽  
Sara J. Johnson ◽  
Lisa K. Nolan
Keyword(s):  
Escherichia Coli ◽  
Southern Blotting ◽  
Virulence Genes ◽  
Complete Sequence ◽  
Economic Losses ◽  
Avian Pathogenic Escherichia Coli ◽  
Prevalence Studies ◽  
E Coli ◽  
Virulence Plasmids ◽  
Pathogenic Escherichia Coli

ABSTRACT Avian pathogenic Escherichia coli (APEC), an extraintestinal pathogenic E. coli causing colibacillosis in birds, is responsible for significant economic losses for the poultry industry. Recently, we reported that the APEC pathotype was characterized by possession of a set of genes contained within a 94-kb cluster linked to a ColV plasmid, pAPEC-O2-ColV. These included sitABCD, genes of the aerobactin operon, hlyF, iss, genes of the salmochelin operon, and the 5′ end of cvaB of the ColV operon. However, the results of gene prevalence studies performed among APEC isolates revealed that these traits were not always linked to ColV plasmids. Here, we present the complete sequence of a 174-kb plasmid, pAPEC-O1-ColBM, which contains a putative virulence cluster similar to that of pAPEC-O2-ColV. These two F-type plasmids share remarkable similarity, except that they encode the production of different colicins; pAPEC-O2-ColV contains an intact ColV operon, and pAPEC-O1-ColBM encodes the colicins B and M. Interestingly, remnants of the ColV operon exist in pAPEC-O1-ColBM, hinting that ColBM-type plasmids may have evolved from ColV plasmids. Among APEC isolates, the prevalence of ColBM sequences helps account for the previously observed differences in prevalence between genes of the “conserved” portion of the putative virulence cluster of pAPEC-O2-ColV and those genes within its “variable” portion. These results, in conjunction with Southern blotting and probing of representative ColBM-positive strains, indicate that this “conserved” cluster of putative virulence genes is primarily linked to F-type virulence plasmids among the APEC isolates studied.

Detection of Bacillus anthracis spores in postal and environmental samples in cases of suspected bioterrorism

2007 ◽  
Vol 31 (1/2) ◽  
pp. 75
Author(s):  
Irena Zdovc ◽  
Matjaz Ocepek ◽  
Vojka Bole Hribovsek ◽  
Igor Gruntar ◽  
Brane Krt ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Environmental Samples ◽  
Bacillus Anthracis Spores

Molecular analysis of spv virulence genes of the salmonella virulence plasmids

1993 ◽  
Vol 7 (6) ◽  
pp. 825-830 ◽  
Author(s):  
Paul A. Gulig ◽  
Hirofumi Danbara ◽  
Donald G. Guiney ◽  
Alistair J. Lax ◽  
Françoise Norel ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Virulence Genes ◽  
Virulence Plasmids ◽  
Salmonella Virulence
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