Various plasmid strategies limit the effect of bacterial restriction-modification systems against conjugation.
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ABSTRACT:
PROVIDER: PRJEB76555 | ENA |
REPOSITORIES: ENA
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Project description:In bacteria, genes conferring antibiotic resistance are mostly carried on conjugative plasmids, mobile genetic elements that spread horizontally between bacterial hosts. Bacteria carry defence systems that defend them against genetic parasites, but how effective these are against plasmid conjugation is poorly understood. Here, we study to what extent restriction-modification (RM) systems-by far the most prevalent bacterial defence systems-act as a barrier against plasmids. Using 10 different RM systems and 13 natural plasmids conferring antibiotic resistance in Escherichia coli, we uncovered variation in defence efficiency ranging from none to 105-fold protection. Further analysis revealed genetic features of plasmids that explain the observed variation in defence levels. First, the number of RM recognition sites present on the plasmids generally correlates with defence levels, with higher numbers of sites being associated with stronger defence. Second, some plasmids encode methylases that protect against restriction activity. Finally, we show that a high number of plasmids in our collection encode anti-restriction genes that provide protection against several types of RM systems. Overall, our results show that it is common for plasmids to encode anti-RM strategies, and that, as a consequence, RM systems form only a weak barrier for plasmid transfer by conjugation.
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Project description:Project description: Plasmids, frequently carried by environmental and pathogenic bacteria, play a critical role in rapid dissemination of antibiotic resistance through conjugation. The use of antibiot-ics further induces this conjugative transmission between bacteria and thereby plays a role in the rise of antibiotic resistance. This highlights the need for a fundamental understanding of the regu-lation of transmission, to limit the problem. In addition, antibiotics induce the bacterial SOS re-sponse, however, whether using SOS as target can reduce conjugation, has been unclear. In this research, we used SOS-inducing compounds, SOS-mutants, conjugation and proteomics, and showed that antibiotic induced conjugation and induction of the SOS response happens through different mechanisms. This provides a new insight, which affects future strategies to control the spread of antibiotics.
2025-05-08 | PXD063721 | Pride
Project description:Plasmid fitness is directed by two orthogonal processes—vertical transfer through cell division and horizontal transfer through conjugation. When considered individually, improvements in either mode of transfer can promote how well a plasmid spreads and persists. Together, however, the metabolic cost of conjugation could create a tradeoff that constrains plasmid evolution. Here we present evidence for the presence, consequences, and molecular basis of a conjugation-growth tradeoff across 40 plasmids derived from clinical E. coli pathogens. We discover that most plasmids operate below a conjugation efficiency threshold for major growth effects, indicating strong natural selection for vertical transfer. Below this threshold, E. coli demonstrates a remarkable growth tolerance to over four orders of magnitude change in conjugation efficiency. This tolerance fades as nutrients become scarce and horizontal transfer attracts a greater share of host resources. Our results provide insight into evolutionary constraints directing plasmid fitness and strategies to combat the spread of antibiotic resistance.
2022-12-23 | GSE219270 | GEO
Project description:Horizontal gene transfer (HGT) is the major mechanism responsible for spread of antibiotic resistance. Antibiotic treatment has been suggested to promote HGT, either by directly affecting the conjugation process itself or by selecting for conjugations subsequent to DNA transfer. However, recent research suggests that the effect of antibiotic treatment on plasmid conjugation frequencies, and hence the spread of resistance plasmids, may have been overestimated. We addressed the question by quantifying transfer proteins and conjugation frequencies of a blaCTX-M-1 encoding IncI1 resistance plasmid in Escherichia coli MG1655 in the presence and absence of therapeutically relevant concentrations of cefotaxime (CTX). Analysis of the proteome by iTRAQ labeling and liquid chromatography tandem mass spectrometry revealed that Tra proteins were significantly up regulated in the presence of CTX. The up-regulation of the transfer machinery was confirmed at the transcriptional level for five selected genes. The CTX treatment did not cause induction of the SOS39 response as revealed by absence of significantly regulated SOS associated proteins in the proteome and no significant up-regulation of recA and sfiA genes. The frequency of plasmid conjugation, measured in an antibiotic free environment, increased significantly when the donor was pre-grown in broth containing CTX compared to growth without this drug, regardless of whether blaCTX-M-1 was located on the plasmid or in trans on the chromosome. The results shows that antibiotic treatment can affect expression of a plasmid conjugation machinery and subsequent DNA transfer.
2017-11-21 | PXD006679 | Pride
Project description:Lactococcal conjugative plasmids are poorly characterized compared to those harbored by numerous other Gram-positive bacteria, despite their significance in dairy fermentations and starter culture development. Furthermore, the transcriptional landscape of these lactococcal conjugation systems and their regulation have not been studied in any detail. Lactococcal plasmids pNP40 and pUC11B possess two genetically distinct and prevalent conjugation systems. Here, we describe the detailed transcriptional analysis of the pNP40 and pUC11B conjugation-associated gene clusters, revealing three and five promoters, respectively, for which the corresponding transcriptional start sites were identified. Regulation of several of these promoters, and therefore conjugation, is shown to involve the individual or concerted activities of the corresponding relaxase and transcriptional repressor(s) encoded by each conjugative plasmid. This work highlights how the conjugative potential of these systems may be unlocked, with significant implications for the starter culture and food fermentation industry.
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Project description:Plasmids are well-known vehicles of antimicrobial resistance (AMR) gene dissemination. Through conjugation, plasmid-encoded AMR genes are spread among neighbouring bacteria, irrespective of their strain or even their species. This process is very concerning from a public health perspective, as plasmid-borne AMR gene outbreaks are often not confined to single species or strains and are therefore more difficult to fully uncover. At the moment, the impact of plasmid conjugation on within-patient plasmid diversity is not well understood. In this work, we will tackle the role of conjugation on within-patient plasmid diversity using a dataset of carbapenemase-producing Enterobacterales. The dataset of 256 sequences originates from bacterial isolates cultured from 115 English patients over 30 months. Each patient has more than one sequence, with at least one sequence carrying an OXA-48 gene, a well-known plasmid-borne carbapenemase-encoding gene. If more than one sequence carries the OXA-48 gene, they are carried in different bacterial hosts. Using a hybrid de novo-on-reference assembly pipeline, we were able to reconstruct the full OXA-48 plasmid from short read sequencing data for 232 of the 256 sequences. Of the 115 patients, 83 (72%) patients had an identical OXA-48 plasmid in two or more sequences. Only two patients carried very different (>200 SNPs) alleles of the OXA-48 plasmid, probably from separate acquisitions. Our study shows that when more than one bacterial host carrying an OXA-48 plasmid is found in a patient, it is most likely that the same plasmid has been shared via conjugation. The event of separate acquisition of different plasmids in different bacterial hosts is highly unlikely in our dataset.
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Project description:Transcription factor EB (TFEB), well characterized as a master regulator of autophagy and lysosomal biogenesis, is translocated to the nucleus and activated by varieties of cellular stresses including starvation and lysosomal damage. However, compared to the starvation condition, the molecular mechanism of TFEB activation by other stress conditions is poorly understood. Previously, we have shown that TFEB activation during lysosomal damage but not starvation condition depends on a subset of autophagy regulators, collectively called ATG conjugation system, whose function is essential for the lipidation of ATG8 proteins. In this study, by time-lapse imaging, we newly identified the presence of ATG conjugation system -independent TFEB regulation which precedes the ATG conjugation system-dependent regulation, designated mode I and mode II, respectively. Consistent with the presence of different modes, our time course transcriptome analysis revealed two different sets of TFEB downstream. Comprehensive interactome analysis of TFEB and subsequent functional screening identified unique regulars of TFEB in each mode: APEX1 for Mode I and CCT7 and/or TRIP6 for Mode II, respectively. APEX1 interacted with TFEB and was required for its protein stability in a manner independent of ATG conjugation system. On the other hand, both CCT7 and TRIP6 were accumulated on lysosomes during lysosomal damage and interacted with TFEB mainly in ATG conjugation system deficient cells, presumably blocking TFEB nuclear translocation. Moreover, we further revealed that TFEB regulatory mechanisms by other cellular stresses such as oxidative stress, proteasome inhibition, mitochondria depolarization, and DNA damage can be classified into either APEX1-mediated Mode I or TRIP6-mediated Mode II. Our results pave the way for a unified understanding TFEB regulatory mechanisms from the perspective of ATG conjugation system under varieties of cellular stresses.
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Project description:ArdB, ArdA, and Ocr proteins inhibit the endonuclease activity of the type I restriction-modification enzymes (RMI). In this study, we evaluated the ability of ArdB, ArdA, and Ocr to inhibit different subtypes of Escherichia coli RMI systems (IA, IB, and IC) as well as two Bacillus licheniformis RMI systems. Furthermore we explored, the antirestriction activity of ArdA, ArdB, and Ocr against a type III restriction-modification system (RMIII) EcoPI and BREX. We found that DNA-mimic proteins, ArdA and Ocr exhibit different inhibition activity, depending on which RM system tested. This effect might be linked to the DNA mimicry nature of these proteins. In theory, DNA-mimic might competitively inhibit any DNA-binding proteins; however, the efficiency of inhibition depend on the ability to imitate the recognition site in DNA or its preferred conformation. In contrast, ArdB protein with an undescribed mechanism of action, demonstrated greater versatility against various RMI systems and provided similar antirestriction efficiency regardless of the recognition site. However, ArdB protein could not affect restriction systems that are radically different from the RMI such as BREX or RMIII. Thus, we assume that the structure of DNA-mimic proteins allows for selective inhibition of any DNA-binding proteins depending on the recognition site. In contrast, ArdB-like proteins inhibit RMI systems independently of the DNA recognition site.
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