scholarly journals Competence for Natural Transformation Is Common among Clinical Strains of Resistant Acinetobacter spp.

2019 ◽  
Vol 7 (2) ◽  
pp. 30 ◽  
Author(s):  
Sara Domingues ◽  
Natasha Rosário ◽  
Ângela Cândido ◽  
Daniela Neto ◽  
Kaare Nielsen ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Natural Transformation ◽  
Clinical Isolates ◽  
Bacterial Populations ◽  
Acinetobacter Species ◽  
Exogenous Dna ◽  
Time Period ◽  
Resistance Patterns ◽  
Important Trait ◽  
Acinetobacter Spp

Horizontal gene transfer events provide the basis for extensive dissemination of antimicrobial resistance traits between bacterial populations. Conjugation is considered to be the most frequent mechanism behind new resistance acquisitions in clinical pathogens but does not fully explain the resistance patterns seen in some bacterial genera. Gene transfer by natural transformation has been described for numerous clinical isolates, including some Acinetobacter species. The main aim of this study was to determine to what extent clinical, resistant Acinetobacter spp. isolates, express competence for natural transformation. Twenty-two clinical Acinetobacter spp. isolates collected over a 16-year time period, from five different geographical separated and/or distinct Portuguese Hospitals were tested for natural transformability. Fourteen isolates, including 11 A. baumannii, 2 A. nosocomialis and 1 Acinetobacter sp., were identified as competent on semisolid media facilitating surface-motility. Competent Acinetobacter isolates were found in all the hospitals tested. Furthermore, osmolarity was shown to influence the uptake of exogenous DNA by competent A. baumannii A118. Our study demonstrates that natural competence is common among clinical isolates of Acinetobacter spp., and hence likely an important trait for resistance acquisition.

scholarly journals CryoEM structure of the type IVa pilus secretin required for natural competence in Vibrio cholerae

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Sara J. Weaver ◽  
Davi R. Ortega ◽  
Matthew H. Sazinsky ◽  
Triana N. Dalia ◽  
Ankur B. Dalia ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Vibrio Cholerae ◽  
Natural Transformation ◽  
Domain Architecture ◽  
Genetic Material ◽  
Surface Binding ◽  
Exogenous Dna ◽  
Insight Into

Abstract Natural transformation is the process by which bacteria take up genetic material from their environment and integrate it into their genome by homologous recombination. It represents one mode of horizontal gene transfer and contributes to the spread of traits like antibiotic resistance. In Vibrio cholerae, a type IVa pilus (T4aP) is thought to facilitate natural transformation by extending from the cell surface, binding to exogenous DNA, and retracting to thread this DNA through the outer membrane secretin, PilQ. Here, we use a functional tagged allele of VcPilQ purified from native V. cholerae cells to determine the cryoEM structure of the VcPilQ secretin in amphipol to ~2.7 Å. We use bioinformatics to examine the domain architecture and gene neighborhood of T4aP secretins in Proteobacteria in comparison with VcPilQ. This structure highlights differences in the architecture of the T4aP secretin from the type II and type III secretion system secretins. Based on our cryoEM structure, we design a series of mutants to reversibly regulate VcPilQ gate dynamics. These experiments support the idea of VcPilQ as a potential druggable target and provide insight into the channel that DNA likely traverses to promote the spread of antibiotic resistance via horizontal gene transfer by natural transformation.

scholarly journals CryoEM structure of the Vibrio cholerae Type IV competence pilus secretin PilQ

2020 ◽  
Author(s):  
Sara J. Weaver ◽  
Matthew H. Sazinsky ◽  
Triana N. Dalia ◽  
Ankur B. Dalia ◽  
Grant J. Jensen
Keyword(s):  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Vibrio Cholerae ◽  
Natural Transformation ◽  
Structural Information ◽  
Genetic Material ◽  
Surface Binding ◽  
Exogenous Dna ◽  
Type Iv

AbstractNatural transformation is the process by which bacteria take up genetic material from their environment and integrate it into their genome by homologous recombination. It represents one mode of horizontal gene transfer and contributes to the spread of traits like antibiotic resistance. In Vibrio cholerae, the Type IV competence pilus is thought to facilitate natural transformation by extending from the cell surface, binding to exogenous DNA, and retracting to thread this DNA through the outer membrane secretin, PilQ. A lack of structural information has hindered our understanding of this process, however. Here, we solved the first ever high-resolution structure of a Type IV competence pilus secretin. A functional tagged allele of VcPilQ purified from native V. cholerae cells was used to determine the cryoEM structure of the PilQ secretin in amphipol to ∼2.7 Å. This structure highlights for the first time key differences in the architecture of the Type IV competence pilus secretin from the Type II and Type III Secretin System secretins. Based on our cryoEM structure, we designed a series of mutants to interrogate the mechanism of PilQ. These experiments provide insight into the channel that DNA likely traverses to promote the spread of antibiotic resistance via horizontal gene transfer by natural transformation. We prove that it is possible to reduce pilus biogenesis and natural transformation by sealing the gate, suggesting VcPilQ as a new drug target.

scholarly journals Role of CommonblaOXA-24/OXA-40-Carrying Platforms and Plasmids in the Spread of OXA-24/OXA-40 among Acinetobacter Species Clinical Isolates

2012 ◽  
Vol 56 (7) ◽  
pp. 3969-3972 ◽  
Author(s):  
Filipa Grosso ◽  
Sandra Quinteira ◽  
Laurent Poirel ◽  
Ângela Novais ◽  
Luísa Peixe
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Restriction Fragment Length Polymorphism ◽  
Fragment Length Polymorphism ◽  
Clonal Expansion ◽  
Clinical Isolates ◽  
Acinetobacter Species ◽  
Content Type ◽  
Restriction Fragment Length

ABSTRACTThe spread of OXA-24/OXA-40 (OXA-24/40)-producingAcinetobacterspp. in the Iberian Peninsula has been strongly influenced by clonal expansion, but the role of horizontal gene transfer has scarcely been explored.blaOXA-24/40-carrying plasmids and genetic environments were characterized in representative (n= 15)Acinetobacterspecies clinical isolates (obtained between 2001 and 2007) byAcinetobacter baumanniiPCR-based replicon typing, sequencing, hybridization, and restriction fragment length polymorphism. Besides the identification ofblaOXA-24/40within the chromosomes of some isolates, the circulation of commonblaOXA-24/40-carrying plasmids (30-kbrepA_AB; 10-kbaci2) and genetic backbones amongAcinetobacterspp. was demonstrated.

scholarly journals Noncanonical Cell-to-Cell DNA Transfer in Thermus spp. Is Insensitive to Argonaute-Mediated Interference

2014 ◽  
Vol 197 (1) ◽  
pp. 138-146 ◽  
Author(s):  
Alba Blesa ◽  
Carolina Elvira César ◽  
Beate Averhoff ◽  
José Berenguer
Keyword(s):  
Natural Transformation ◽  
Thermus Thermophilus ◽  
Rapid Evolution ◽  
Extreme Thermophile ◽  
Bacterial Populations ◽  
Exogenous Dna ◽  
Content Type ◽  
Naked Dna ◽  
Transfer Mechanisms ◽  
Dna Acquisition

Horizontal gene transfer drives the rapid evolution of bacterial populations. Classical processes that promote the lateral flow of genetic information are conserved throughout the prokaryotic world. However, some species have nonconserved transfer mechanisms that are not well known. This is the case for the ancient extreme thermophileThermus thermophilus. In this work, we show thatT. thermophilusstrains are capable of exchanging large DNA fragments by a novel mechanism that requires cell-to-cell contacts and employs components of the natural transformation machinery. This process facilitates the bidirectional transfer of virtually any DNA locus but favors by 10-fold loci found in the megaplasmid over those in the chromosome. In contrast to naked DNA acquisition by transformation, the system does not activate the recently described DNA-DNA interference mechanism mediated by the prokaryotic Argonaute protein, thus allowing the organism to distinguish between DNA transferred from a mate and exogenous DNA acquired from unknown hosts. This Argonaute-mediated discrimination may be tentatively viewed as a strategy for safe sharing of potentially “useful” traits by the components of a given population ofThermusspp. without increasing the genome sizes of its individuals.

scholarly journals Pseudomonas aeruginosa is capable of natural transformation in biofilms

Microbiology ◽  
2020 ◽  
Vol 166 (10) ◽  
pp. 995-1003 ◽  
Author(s):  
Laura M. Nolan ◽  
Lynne Turnbull ◽  
Marilyn Katrib ◽  
Sarah R. Osvath ◽  
Davide Losa ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Species ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Extracellular Dna ◽  
Virulence Determinants ◽  
Bacterial Populations ◽  
Exogenous Dna ◽  
Content Type ◽  
Link Type

Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologues of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type-IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa .

scholarly journals Interbacterial transfer of carbapenem resistance and large antibiotic resistance islands by natural transformation in pathogenic Acinetobacter

2021 ◽  
Author(s):  
Anne-Sophie Godeux ◽  
Elin Svedholm ◽  
Samuel Barreto ◽  
Agnese Lupo ◽  
Marisa Haenni ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Natural Transformation ◽  
Antibiotic Resistance Genes ◽  
Carbapenem Resistance ◽  
Predatory Behavior ◽  
Clinical Isolates

Acinetobacter baumannii infection poses a major health threat with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intra-, but also inter-strain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4, AbaR1) than providing the same bacteria with high quantities of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genome of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombination and results from both spontaneous release and interbacterial predatory behavior. Natural transformation should be considered as a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii.

scholarly journals Pseudomonas aeruginosa is capable of natural transformation in biofilms

2019 ◽  
Author(s):  
Laura M. Nolan ◽  
Lynne Turnbull ◽  
Marilyn Katrib ◽  
Sarah R. Osvath ◽  
Davide Losa ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Extracellular Dna ◽  
Genome Plasticity ◽  
Virulence Determinants ◽  
Bacterial Populations ◽  
Exogenous Dna ◽  
Type Iv ◽  
High Degree

AbstractNatural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologs of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa.

scholarly journals Surgical Site Infection Following Caesarean Section by Acinetobacter Species: A Report from a Hyperendemic Setting in the Brazilian Amazon Region

2021 ◽  
Vol 9 (4) ◽  
pp. 743
Author(s):  
Blenda Gonçalves Cabral ◽  
Danielle Murici Brasiliense ◽  
Ismari Perini Furlaneto ◽  
Yan Corrêa Rodrigues ◽  
Karla Valéria Batista Lima
Keyword(s):  
Caesarean Section ◽  
Surgical Site Infection ◽  
Carbapenem Resistance ◽  
Brazilian Amazon ◽  
Amazon Region ◽  
Site Infection ◽  
Acinetobacter Species ◽  
Brazilian Amazon Region ◽  
Acinetobacter Spp ◽  
The Impact

Surgical site infection (SSI) following caesarean section is associated with increased morbidity, mortality, and significant health care costs. This study evaluated the epidemiological, clinical, and microbiological features of Acinetobacter spp. in women with SSIs who have undergone caesarean section at a referral hospital in the Brazilian Amazon region. This study included 69 women with post-caesarean SSI by Acinetobacter spp. admitted to the hospital between January 2012 and May 2015. The 69 Acinetobacter isolates were subjected to molecular species identification, antimicrobial susceptibility testing, detection of carbapenemase-encoding genes, and genotyping. The main complications of post-caesarean SSI by Acinetobacter were inadequate and prolonged antibiotic therapy, sepsis, prolonged hospitalization, and re-suture procedures. A. baumannii, A. nosocomialis and A. colistiniresistens species were identified among the isolates. Carbapenem resistance was associated with OXA-23-producing A. baumannii isolates and IMP-1-producing A. nosocomialis isolate. Patients with multidrug-resistant A. baumannii infection showed worse clinical courses. Dissemination of persistent epidemic clones was observed, and the main clonal complexes (CC) for A. baumannii were CC231 and CC236 (Oxford scheme) and CC1 and CC15 (Pasteur scheme). This is the first report of a long-term Acinetobacter spp. outbreak in women who underwent caesarean section at a Brazilian hospital. This study demonstrates the impact of multidrug resistance on the clinical course of post-caesarean infections.

scholarly journals An Evolutionary Link between Natural Transformation and CRISPR Adaptive Immunity

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Peter Jorth ◽  
Marvin Whiteley
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Bacterial Diversity ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Comparative Genomic ◽  
Content Type ◽  
Immune Systems ◽  
Adaptive Immune ◽  
Adaptive Immune Systems

ABSTRACTNatural transformation by competent bacteria is a primary means of horizontal gene transfer; however, evidence that competence drives bacterial diversity and evolution has remained elusive. To test this theory, we used a retrospective comparative genomic approach to analyze the evolutionary history ofAggregatibacter actinomycetemcomitans, a bacterial species with both competent and noncompetent sister strains. Through comparative genomic analyses, we reveal that competence is evolutionarily linked to genomic diversity and speciation. Competence loss occurs frequently during evolution and is followed by the loss of clustered regularly interspaced short palindromic repeats (CRISPRs), bacterial adaptive immune systems that protect against parasitic DNA. Relative to noncompetent strains, competent bacteria have larger genomes containing multiple rearrangements. In contrast, noncompetent bacterial genomes are extremely stable but paradoxically susceptible to infective DNA elements, which contribute to noncompetent strain genetic diversity. Moreover, incomplete noncompetent strain CRISPR immune systems are enriched for self-targeting elements, which suggests that the CRISPRs have been co-opted for bacterial gene regulation, similar to eukaryotic microRNAs derived from the antiviral RNA interference pathway.IMPORTANCEThe human microbiome is rich with thousands of diverse bacterial species. One mechanism driving this diversity is horizontal gene transfer by natural transformation, whereby naturally competent bacteria take up environmental DNA and incorporate new genes into their genomes. Competence is theorized to accelerate evolution; however, attempts to test this theory have proved difficult. Through genetic analyses of the human periodontal pathogenAggregatibacter actinomycetemcomitans, we have discovered an evolutionary connection between competence systems promoting gene acquisition and CRISPRs (clustered regularly interspaced short palindromic repeats), adaptive immune systems that protect bacteria against genetic parasites. We show that competentA. actinomycetemcomitansstrains have numerous redundant CRISPR immune systems, while noncompetent bacteria have lost their CRISPR immune systems because of inactivating mutations. Together, the evolutionary data linking the evolution of competence and CRISPRs reveals unique mechanisms promoting genetic heterogeneity and the rise of new bacterial species, providing insight into complex mechanisms underlying bacterial diversity in the human body.

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