ORCID Profile
0000-0003-1364-6911
Current Organisation
Fraunhofer Institute for Cell Therapy and Immunology
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Publisher: Frontiers Media SA
Date: 03-12-2020
DOI: 10.3389/FMICB.2020.579802
Abstract: Acinetobacter baumannii is of major clinical importance as the bacterial pathogen often causes hospital acquired infections, further complicated by the high prevalence of antibiotic resistant strains. Aside from natural tolerance to certain antibiotic classes, resistance is often acquired by the exchange of genetic information via conjugation but also by the high natural competence exhibited by A. baumannii . In addition, bacteriophages are able to introduce resistance genes but also toxins and virulence factors via phage mediated transduction. In this work, we analyzed the complete genomes of 177 A. baumannii strains for the occurrence of prophages, and analyzed their taxonomy, size and positions of insertion. Among all the prophages that were detected, Siphoviridae and Myoviridae were the two most commonly found families, while the average genome size was determined to be approximately 4 Mbp. Our data shows the wide variation in the number of prophages in A. baumannii genomes and the prevalence of certain prophages within strains that are most “successful” or potentially beneficial to the host. Our study also revealed that only two specific sites of insertion within the genome of the host bacterium are being used, with few exceptions only. Lastly, we analyzed the existence of genes that are encoded in the prophages, which may confer antimicrobial resistance (AMR). Several phages carry AMR genes, including OXA-23 and NDM-1, illustrating the importance of lysogenic phages in the acquisition of resistance genes.
Publisher: American Society for Microbiology
Date: 12-02-2021
DOI: 10.1128/AEM.01979-20
Abstract: Delivery of therapeutic compounds to the site of action is crucial. While many chemical substances such as beta-lactam antibiotics can reach therapeutic levels in most parts throughout the human body after administration, substances of higher molecular weight such as therapeutic proteins may not be able to reach the site of action (e.g., an infection) and are therefore ineffective.
Publisher: American Society for Microbiology
Date: 07-10-2021
DOI: 10.1128/MRA.00669-21
Abstract: Phab24 was isolated from river water in Zhejiang Province, China, and exhibits lytic activity against clinical isolates of the nosocomial pathogen Acinetobacter baumannii (X. Wang, B. Loh, Y. Yu, X. Hua, S. Leptihn, bioRxiv, 2021, 0.1101/2021.07.23.453473 ). The bacteriophage belongs to the Myoviridae family and has a double-stranded DNA (dsDNA) genome sequence that is 93,604 bp long, containing 172 open reading frames (ORFs).
Publisher: Informa UK Limited
Date: 2021
Publisher: Wiley
Date: 24-03-2010
Publisher: Frontiers Media SA
Date: 26-06-2020
Publisher: Oxford University Press (OUP)
Date: 08-02-2014
DOI: 10.1093/NAR/GKU129
Publisher: MDPI AG
Date: 18-01-2022
DOI: 10.3390/V14020167
Abstract: Phages utilize lysis systems to allow the release of newly assembled viral particles that kill the bacterial host. This is also the case for phage AP1, which infects the rice pathogen Acidovorax oryzae. However, how lysis occurs on a molecular level is currently unknown. We performed in silico bioinformatics analyses, which indicated that the lysis cassette contains a holin (HolAP) and endolysin (LysAP), which are encoded by two adjacent genes. Recombinant expression of LysAP caused Escherichia coli lysis, while HolAP arrested growth. Co-expression of both proteins resulted in enhanced lysis activity compared to the in idual proteins alone. Interestingly, LysAP contains a C-terminal region transmembrane domain, which is different from most known endolysins where a N-terminal hydrophobic region is found, with the potential to insert into the membrane. We show that the C-terminal transmembrane domain is crucial for protein localization and bacterial lysis in phage AP1. Our study characterizes the new phage lysis cassette and the mechanism to induce cell disruption, giving new insight in the understanding of phage life cycles.
Publisher: American Society for Microbiology
Date: 02-12-2021
DOI: 10.1128/MRA.01043-21
Abstract: Pseudomonas aeruginosa is a major public health concern, as drug-resistant strains increase mortality in hospital-acquired infections. We report the isolation and complete genome sequences of four lytic bacteriophages that target clinical multidrug-resistant P. aeruginosa strains.
Publisher: MDPI AG
Date: 31-03-2017
DOI: 10.20944/PREPRINTS201703.0232.V1
Abstract: In contrast to lytic phages, filamentous phages are assembled in the inner membrane and secreted across the bacterial envelope without killing the host. For assembly and extrusion of the phage across the host cell wall, filamentous phages code for membrane-embedded morphogenesis proteins. In the outer membrane of E. coli, the protein gp4 forms a pore-like complex, while gp1 and gp11 form a complex in the inner membrane of the host. By comparing sequences with other filamentous phages, we identified putative Walker A and B motifs in gp1 with a conserved lysine in the Walker A motif (K14), and a glutamic and aspartic acid in the Walker B motif (D88, E89). In this work we demonstrate that both, Walker A and Walker B, are essential for phage production. The crucial role of these key residues suggest that gp1 is likely to be a molecular motor driving phage assembly. We further identified essential residues for the function of the assembly complex. Mutations in three out of six cysteine residues abolish phage production. Similarly, two out of six conserved glycine residues are crucial for gp1 function. We hypothesise that the residues represent molecular hinges allowing domain movement for nucleotide binding and phage assembly.
Publisher: Frontiers Media SA
Date: 22-04-2021
DOI: 10.3389/FMICB.2021.602902
Abstract: Phage therapy represents a possible treatment option to cure infections caused by multidrug-resistant bacteria, including methicillin and vancomycin-resistant Staphylococcus aureus , to which most antibiotics have become ineffective. In the present study, we report the isolation and complete characterization of a novel phage named JD219 exhibiting a broad host range able to infect 61 of 138 clinical strains of S. aureus tested, which included MRSA strains as well. The phage JD419 exhibits a unique morphology with an elongated capsid and a flexible tail. To evaluate the potential of JD419 to be used as a therapeutic phage, we tested the ability of the phage particles to remain infectious after treatment exceeding physiological pH or temperature. The activity was retained at pH values of 6.0–8.0 and below 50°C. As phages can contain virulence genes, JD419’s complete genome was sequenced. The 45509 bp genome is predicted to contain 65 ORFs, none of which show homology to any known virulence or antibiotic resistance genes. Genome analysis indicates that JD419 is a temperate phage, despite observing rapid replication and lysis of host strains. Following the recent advances in synthetic biology, JD419 can be modified by gene engineering to remove prophage-related genes, preventing potential lysogeny, in order to be deployed as a therapeutic phage.
Publisher: Cold Spring Harbor Laboratory
Date: 09-11-2020
DOI: 10.1101/2020.11.09.370866
Abstract: As an antimicrobial therapy, therapeutic phages, also known as “Phage therapy” are able to inactivate multi-drug resistant bacteria such as methicillin and vancomycin resistant S. aureus and thus present a possible treatment for infections that are otherwise incurable. In this paper, we present a novel phage called JD419, which has a remarkably wide host-range. The virulent phage JD419 exhibits an elongated capsid and was able to infect and lyse 83 of all 129 tested clinical strains (64.3%) of multi-drug resistant S. aureus including MRSA. To evaluate the potential as a therapeutic phage, we tested the ability of phage JD419 to remain infectious after treatment exceeding physiological pH or temperature. The lytic activity of the phage was retained at pH values of 6.0-8.0 and at temperatures below 50°C. As phages sometimes contain virulence genes, we sequenced the complete genome of JD419. The 45509 bp genome contains a predicted 65 ORFs, none of which show homology to any known virulence or antibiotic resistance genes. Our study illustrates that Staphylococcus phage JD419 has the potential to be used for diagnostic, prophylaxic and therapeutic purposes.
Publisher: American Society for Microbiology
Date: 02-12-2021
DOI: 10.1128/MRA.00685-21
Abstract: Geezett was isolated from hospital sewage in Hangzhou, China, and exhibits lytic activity against clinical isolates of the nosocomial pathogen Klebsiella pneumoniae . The bacteriophage is a myovirus and has a double-stranded DNA (dsDNA) genome 50,707 bp long, containing 79 open reading frames (ORFs).
Publisher: Frontiers Media SA
Date: 05-08-2020
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.MOLIMM.2007.09.030
Abstract: Sterile-alpha and Armadillo motif containing protein (SARM) was recently identified as the fifth member of the Toll-like receptor (TLR) adaptor family. Whilst the Caenorhabditis elegans SARM homologue, TIR-1, is crucial for efficient immune responses against bacterial infections, human SARM was demonstrated to function as a specific inhibitor of TRIF-dependent TLR signaling. The opposing role of SARM in C. elegans and human is intriguing, prompting us to seek clarification on the enigmatic function of SARM in an ancient species which relies solely on innate immunity for survival. Here, we report the discovery of a primitive but functional SARM (CrSARM) in the immune defense of a "living fossil", the horseshoe crab, Carcinoscorpius rotundicauda. CrSARM shares numerous signature motifs and displays significant homology with vertebrate and invertebrate SARM homologues. CrSARM downregulates TRIF-dependent TLR signaling suggesting the conservation of SARM function from horseshoe crab to human. During infection by Pseudomonas aeruginosa, CrSARM is rapidly upregulated within 3h and strongly repressed at 6h, coinciding with the timing of bacterial clearance, thus demonstrating its dynamic role in innate immunity. Furthermore, yeast-two-hybrid screening revealed several potential interaction partners of CrSARM implying the role of SARM in downregulating TLR signaling events. Altogether, our study shows that, although C. elegans SARM upregulates immune signaling, its disparate role as a suppressor of TLR signaling, specifically via TRIF and not MyD88, is well-conserved from horseshoe crab to human.
Publisher: American Society for Microbiology
Date: 17-11-2022
DOI: 10.1128/MRA.00740-22
Abstract: We describe the complete genome sequence of bacteriophage Motto, which infects clinical strains of Pseudomonas aeruginosa . Motto is a T1-like siphovirus related to members of the family Drexlerviridae and has a capsid width of ~57 nm and a tail length of ~255 nm. The 49.9-kb genome contains 84 protein-coding genes.
Publisher: Frontiers Media SA
Date: 05-07-2021
DOI: 10.3389/FMICB.2021.674974
Abstract: Many strains of the opportunistic pathogen Pseudomonas aeruginosa have acquired resistance to multiple antibiotics. Carbapenem-resistant P. aeruginosa poses a global healthcare problem due to limited therapeutic options for the treatment of infections. Plasmids and integrative and conjugative elements (ICEs) are the major vectors of antibiotic-resistance gene transfer. In our study, four carbapenem-resistant strains of P. aeruginosa were isolated from the same patient in a tertiary referral hospital in China, one of these was resistant to gentamicin and tobramycin. In this strain P33, we observed a non-transferable plasmid, pP33-2, carrying a novel bla KPC−2 gene segment (IS Kpn27 - bla KPC−2 -IS Kpn6 - korC -ORF- klcA -IS 26 ), which we concluded to have been formed by IS 26 -mediated gene cluster translocation. In addition, by comparing the chromosomes of the P. aeruginosa strains that belong to the same sequence type, we identified an ICE, ICEP33, adjacent to a prophage. The att L site of ICEP33 is identical to the terminal part of the att R site of the prophage. The ICEP33 element contains the transposon Tn 6203 , which encodes antibiotic and metal resistance genes. The insertion of ICEP33 in the chromosome mediates resistance to multiple antibiotics. Our study contributes to the understanding of the acquisition of antibiotic resistance in P. aeruginosa facilitated by mobile genetic elements.
Publisher: Cold Spring Harbor Laboratory
Date: 10-2013
Abstract: Nonsense-mediated mRNA decay (NMD) is a eukaryotic quality control mechanism that detects aberrant mRNAs containing nonsense codons and induces their rapid degradation. This degradation is mediated by SMG6, an NMD-specific endonuclease, as well as the SMG5 and SMG7 proteins, which recruit general mRNA decay enzymes. However, it remains unknown which specific decay factors are recruited and whether this recruitment is direct. Here, we show that SMG7 binds directly to POP2, a catalytic subunit of the CCR4–NOT deadenylase complex, and elicits deadenylation-dependent decapping and 5′-to-3′ decay of NMD targets. Accordingly, a catalytically inactive POP2 mutant partially suppresses NMD in human cells. The SMG7–POP2 interaction is critical for NMD in cells depleted of SMG6, indicating that SMG7 and SMG6 act redundantly to promote the degradation of NMD targets. We further show that UPF1 provides multiple binding sites for decapping factors. These data unveil a missing direct physical link between NMD and the general mRNA decay machinery and indicate that NMD employs erse and partially redundant mechanisms to ensure robust degradation of aberrant mRNAs.
Publisher: Elsevier BV
Date: 12-2010
Publisher: MDPI AG
Date: 28-09-2021
DOI: 10.3390/V13101949
Abstract: Most endolysins of dsDNA phages are exported by a holin-dependent mechanism, while in some cases endolysins are exported via a holin-independent mechanism. However, it is still unclear whether the same endolysins can be exported by both holin-dependent and holin-independent mechanisms. This study investigated the lysis system of OP2-like phage X2 infecting Xanthomonas oryzae pv. oryzae, causing devastating bacterial leaf blight disease in rice. Based on bioinformatics and protein biochemistry methods, we show that phage X2 employs the classic "holin-endolysin" lysis system. The endolysin acts on the cell envelope and exhibits antibacterial effects in vitro, while the holin facilitates the release of the protein into the periplasm. We also characterized the role of the transmembrane domain (TMD) in the translocation of the endolysin across the inner membrane. We found that the TMD facilitated the translocation of the endolysin via the Sec secretion system. The holin increases the efficiency of protein release, leading to faster and more efficient lysis. Interestingly, in E. coli, the expression of either holin or endolysin with TMDs resulted in the formation of long rod shaped cells. We conclude that the TMD of X2-Lys plays a dual role: One is the transmembrane transport while the other is the inhibition of cell ision, resulting in larger cells and thus in a higher number of released viruses per cell.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-07-2020
Publisher: Cold Spring Harbor Laboratory
Date: 21-09-2022
DOI: 10.1101/2022.09.21.508815
Abstract: Prophages, i.e. dormant viruses residing in bacterial cells, are not just passive passengers in the bacterial host. Several prophage-encoded genes have been shown to be contributors to bacterial virulence by mediating antimicrobial resistance or by providing toxins. Other prophage genes exhibit beneficial effects on the host by modulating e.g. motility or biofilm formation. In this study, we used an in vivo phage assembly assay and tested an extensive array of single point mutations or their combinations found in Zot, the zonula occludens toxin encoded by the Vibrio cholerae phage CTXϕ. The assay makes use of the highly homologous Zot-like protein g1p of the filamentous Coliphage M13, a motor protein that mediates the trans-envelope assembly and secretion of filamentous phages. We also measured the in vitro ATP hydrolysis of purified proteins, and quantified virus production in V. cholerae mediated by Zot or the Zot-like protein of the two Vibrio phages CTXϕ and VFJϕ. In addition, we investigated sequence variations of the Walker motifs in Vibrio species using bioinformatics method, and revealed the molecular basis of ATP binding using molecular docking and molecular dynamics simulation based on the structure predicted by AlphaFold2. Our data indicates that g1p proteins in Vibrio can easily accumulate deleterious mutations and likely lose the ability to efficiently hydrolyse ATP, while the CTXϕ Zot was further exapted to now act as an auxiliary toxin during the infection by Vibrio cholerae .
Publisher: Informa UK Limited
Date: 02-2013
DOI: 10.4161/RNA.23018
Publisher: Wiley
Date: 26-03-2019
DOI: 10.1111/MMI.14187
Abstract: With the recently awarded Nobel Prize to the inventor of Phage Display, George Smith, the technique has once more gained attention. However, one should not forget about the biology behind the method. Almost always ignored is how the structure of this bacterial virus is assembled. In contrast to lytic phages, filamentous phages are constantly being extruded through the bacterial membranes without lysis. Such filamentous phages are found in all aquatic environments, such as rivers and lakes, in the deep sea, in arctic ice, in hot springs and, associated with their hosts, in plants and animals including humans. While most filamentous phages infect Gram-negative hosts, inoviruses of Gram-positive hosts have also been described. Despite being among the minority within the phage family with an estimate of less than 5%, filamentous phages are real parasites as they exist at the expense of the host, but do not kill it. In contrast to lytic bacteriophages, filamentous phages are assembled in the host's membrane and extruded across the cellular envelope while the bacterium continues to grow. In this review, we focus on this complex and yet poorly understood process of assembly and secretion of filamentous phages.
Publisher: Cold Spring Harbor Laboratory
Date: 23-07-2021
DOI: 10.1101/2021.07.23.453473
Abstract: Few emergency-use antibiotics remain for the treatment of multidrug-resistant bacterial infections. Infections with resistant bacteria are becoming increasingly common. Phage therapy has reemerged as a promising strategy to treat such infections, as microbial viruses are not affected by bacterial resistance to antimicrobial compounds. However, phage therapy is impeded by rapid emergence of phage-resistant bacteria during therapy. In this work, we studied phage-resistance of colistin sensitive and resistant A. baumannii strains. Using whole genome sequencing, we determined that phage resistant strains displayed mutations in genes that alter the architecture of the bacterial envelope. In contrast to previous studies where phage-escape mutants showed decreased binding of phages to the bacterial envelope, we obtained several not uninfectable isolates that allowed similar phage adsorption compared to the susceptible strain. When phage-resistant bacteria emerged in the absence of antibiotics, we observed that the colistin resistance levels often decreased, while the antibiotic resistance mechanism per se remained unaltered. In particular the two mutated genes that conveyed phage resistance, a putative amylovoran-biosynthesis and a lipo-oligosaccharide (LOS) biosynthesis gene, impact colistin resistance as the mutations increased sensitivity to the antibiotic.
Publisher: American Chemical Society (ACS)
Date: 21-12-2016
DOI: 10.1021/ACSCHEMBIO.6B01085
Abstract: Protein insertion into membranes is a process occurring in every cell and every cellular compartment. Yet, many thermodynamic aspects of this fundamental biophysical process are not well understood. We investigated physicochemical parameters that influence protein insertion using the model protein KcsA, a 2-transmembrane ion channel. To understand what drives insertion and to identify in idual steps of protein integration into a highly apolar environment, we investigated the contribution of electrostatic interactions and lipid composition on protein insertion on a single molecule level. We show that insertion of KcsA is spontaneous and directional as the cytosolic part of the protein does not translocate across the membrane barrier. Surprisingly, not hydrophobic residues but charged amino acids are crucial for the insertion of the unfolded protein into the membrane. Our results demonstrate the importance of electrostatic interactions between membrane and protein during the insertion process of hydrophobic polypeptides into the apolar membrane. On the basis of the observation that negatively charged lipids increase insertion events while high ionic strength in the surrounding aqueous phase decreases insertion events, a two-step mechanism is proposed. Here, an initial electrostatic attraction between membrane and protein represents the first step prior to insertion of hydrophobic residues into the hydrocarbon core of the membrane.
Publisher: MDPI AG
Date: 09-04-2017
DOI: 10.3390/V9040073
Publisher: American Society for Microbiology
Date: 25-02-2016
Abstract: We report here the draft genome sequence of Pyrodictium occultum PL19 T , a marine hyperthermophilic archaeon. The genome provides insights into molecular and cellular adaptation mechanisms to life in extreme environments and the evolution of early organisms on Earth.
Publisher: Future Medicine Ltd
Date: 06-2022
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2020
DOI: 10.1101/2020.10.26.355222
Abstract: Acinetobacter baumannii is of major clinical importance as the bacterial pathogen often causes hospital acquired infections, further complicated by the high prevalence of antibiotic resistant strains. Aside from natural tolerance to certain antibiotic classes, resistance is often acquired by the exchange of genetic information via conjugation but also by the high natural competence exhibited by A. baumannii . In addition, bacteriophages are able to introduce resistance genes but also toxins and virulence factors via phage mediated transduction. In this work, we analysed the complete genomes of 177 A. baumannii strains for the occurrence of prophages, and analysed their taxonomy, size and positions of insertion. Among all the prophages that were detected, Siphoviridae and Myoviridae were the two most commonly found families, while the average genome size was determined as 3.98 Mbp. Our data shows the wide variation in the number of prophages in A. baumannii genomes and the prevalence of certain prophages within strains that are most “successful” or potentially beneficial to the host. Our study also revealed that only two specific sites of insertion within the genome of the host bacterium are being used, with few exceptions only. Lastly, we analysed the existence of genes that are encoded in the prophages, which confer antimicrobial resistance (AMR). Several phages carry AMR genes, including OXA-23 and NDM-1, illustrating the importance of lysogenic phages in the acquisition of resistance genes.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 31-01-2020
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.MOLCEL.2014.03.034
Abstract: CCR4-NOT is a major effector complex in miRNA-mediated gene silencing. It is recruited to miRNA targets through interactions with tryptophan (W)-containing motifs in TNRC6/GW182 proteins and is required for both translational repression and degradation of miRNA targets. Here, we elucidate the structural basis for the repressive activity of CCR4-NOT and its interaction with TNRC6/GW182s. We show that the conserved CNOT9 subunit attaches to a domain of unknown function (DUF3819) in the CNOT1 scaffold. The resulting complex provides binding sites for TNRC6/GW182, and its crystal structure reveals tandem W-binding pockets located in CNOT9. We further show that the CNOT1 MIF4G domain interacts with the C-terminal RecA domain of DDX6, a translational repressor and decapping activator. The crystal structure of this complex demonstrates striking similarity to the eIF4G-eIF4A complex. Together, our data provide the missing physical links in a molecular pathway that connects miRNA target recognition with translational repression, deadenylation, and decapping.
Publisher: Springer Science and Business Media LLC
Date: 06-2014
DOI: 10.1038/NSMB.2837
Abstract: The PAN2-PAN3 complex functions in general and microRNA-mediated mRNA deadenylation. However, mechanistic insight into PAN2 and its complex with the asymmetric PAN3 dimer is lacking. Here, we describe crystal structures that show that Neurospora crassa PAN2 comprises two independent structural units: a C-terminal catalytic unit and an N-terminal assembly unit that engages in a bipartite interaction with PAN3 dimers. The catalytic unit contains the exonuclease domain in an intimate complex with a potentially modulatory ubiquitin-protease-like domain. The assembly unit contains a WD40 propeller connected to an adaptable linker. The propeller contacts the PAN3 C-terminal domain, whereas the linker reinforces the asymmetry of the PAN3 dimer and prevents the recruitment of a second PAN2 molecule. Functional data indicate an essential role for PAN3 in coordinating PAN2-mediated deadenylation with subsequent steps in mRNA decay, which lead to complete mRNA degradation.
Publisher: American Society for Microbiology
Date: 20-09-2022
DOI: 10.1128/AAC.00506-22
Abstract: Bacteriophages and bacteriophage-derived peptidoglycan hydrolases (endolysins) present promising alternatives for the treatment of infections caused by multidrug resistant Gram-negative and Gram-positive pathogens. In this study, Gp105, a putative lysozyme murein hydrolase from Enterobacter phage myPSH1140 was characterized in silico, in vitro as well as in vivo using the purified protein.
Publisher: MDPI AG
Date: 13-08-2022
DOI: 10.3390/V14081770
Abstract: Plants grow together with microbes that have both negative and positive impacts on the host, while prokaryotes are in turn also hosts for viruses, co-evolving together in a complex interrelationship. Most research focuses on the interaction of either bacterial pathogens interacting with the plant host, or the impact on viruses on their pathogenic bacterial hosts. Few studies have investigated the co-evolution of bacterial pathogens with their host plants as well as with their bacterial viruses. In this work, we aimed to identify the genes that were associated with both phage sensitivity and host pathogenicity of the bacterium Xanthomonas oryzae pv. oryzae (Xoo), which is the most important bacterial rice pathogen. Using the Tn5 transposon mutation technology, we created a library of Xoo strain C2 comprising 4524 mutants, which were subsequently tested for phage infectability. The phage infection tests showed that less than 1% of the mutants (n = 36) were resistant to phage infection, which was attributed to the Tn5 insertion in 19 genes. Interestingly, three out of 19 genes that conveyed resistance to the phage resulted in reduced pathogenicity to rice seedlings compared to the wild type. We identified three genes involved in both phage infection and bacterial virulence, which were studied by knockout mutants and complementation experiments. All of the three knockout mutants were resistant to infection by phage X2, while the complemented strains restored the susceptibility to the bacterial virus. Surprisingly, the genes are also essential for pathogenicity, which we confirmed by single knockout mutants corresponding to the Tn5 mutants. All three genes are involved in lipopolysaccharide synthesis, thus changing the cell envelope surface molecule composition. Our work shows a possible balance in terms of the connection between bacterial virulence and phage resistance, supporting the deployment of phages for the biocontrol of plant pathogens.
Publisher: Frontiers Media SA
Date: 22-12-2020
DOI: 10.3389/FMICB.2020.604710
Abstract: Salmonella is an important food pathogen that can cause severe gastroenteritis with more than 600,000 deaths globally every year. Colistin (COL), a last-resort antibiotic, is ineffective in bacteria that carry a functional mcr-1 gene, which is often spread by conjugative plasmids. Our work aimed to understand the prevalence of the mcr-1 gene in clinical isolates of Salmonella , as the frequency of occurrence of the mcr-1 gene is increasing globally. Therefore, we analyzed 689 clinical strains, that were isolated between 2009 and late 2018. The mcr-1 gene was found in six strains, which we analyzed in detail by whole genome sequencing and antibiotic susceptibility testing, while we also provide the clinical information on the patients suffering from an infection. The genomic analysis revealed that five strains had plasmid-encoded mcr-1 gene located in four IncHI2 plasmids and one IncI2 plasmid, while one strain had the chromosomal mcr-1 gene originated from plasmid. Surprisingly, in two strains the mcr-1 genes were inactive due to disruption by insertion sequences (ISs): IS Apl1 and IS Vsa5 . A detailed analysis of the plasmids revealed a multitude of ISs, most commonly IS 26 . The IS contained genes that meditate broad resistance toward most antibiotics underlining their importance of the mobile elements, also with respect to the spread of the mcr-1 gene. Our study revealed potential reservoirs for the transmission of COL resistance and offers insights into the evolution of the mcr-1 gene in Salmonella .
Publisher: Elsevier BV
Date: 12-2020
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: Germany
Start Date: 2019
End Date: 2021
Funder: China Postdoctoral Science Foundation
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