Project description:Transient plasmid transfection is common approach for studies in cultured mammalian cells. To examine behavior of transfected plasmids, we analyzed their transcriptional landscape by deep sequencing. We found that plasmids generate different levels of transcripts virtually everywhere. Spurious transcription may have undesirable effects as some co-transfected plasmids inhibited expression of luciferase reporters in a dose-dependent manner. In one case, we attributed this effect to kan/neo resistance cassette, which generated a unique population of edited sense and antisense small RNAs. The unexpected complexity of expression of transiently transfected plasmids highlights the importance of appropriate experimental controls.
Project description:Transient plasmid transfection is common approach for studies in cultured mammalian cells. To examine behavior of transfected plasmids, we analyzed their transcriptional landscape by deep sequencing. We found that plasmids generate different levels of transcripts virtually everywhere. Spurious transcription may have undesirable effects as some co-transfected plasmids inhibited expression of luciferase reporters in a dose-dependent manner. In one case, we attributed this effect to kan/neo resistance cassette, which generated a unique population of edited sense and antisense small RNAs. The unexpected complexity of expression of transiently transfected plasmids highlights the importance of appropriate experimental controls. HEK293 cells (human origin) transiently transfected with 4 various plasmids
Project description:Antibiotic resistance is exacerbated by the exchange of antibiotic resistance genes (ARGs) between microbes from diverse habitats. Plasmids are important ARGs mobile elements and are spread by horizontal gene transfer (HGT). In this study, we demonstrated the presence of multi-resistant plasmids from inhalable particulate matter (PM) and its effect on gene horizontal transfer. Three transferable multi-resistant plasmids were identified from PM in a hospital, using conjugative mating assays and nanopore sequencing. pTAir-3 contained 26 horizontal transfer elements and 10 ARGs. Importantly pTAir-5 harbored carbapenem resistance gene (blaOXA) which shows homology to plasmids from human and pig commensal bacteria, thus indicating that PM is a media for antibiotic resistant plasmid spread. In addition, 125 μg/mL PM2.5 and PM10 significantly increased the conjugative transfer rate by 110% and 30%, respectively, and augmented reactive oxygen species (ROS) levels. Underlying mechanisms were revealed by identifying the upregulated expressional levels of genes related to ROS, SOS, cell membranes, pilus generation, and transposition via genome-wide RNA sequencing. The study highlights the airborne spread of multi-resistant plasmids and the impact of inhalable PM on the horizontal transfer of antibiotic resistance.
Project description:The HIV-1 Gag protein orchestrates all steps of virion genesis, including RNA recruitment into virions. However, the identities of specific RNA sequences recognized by Gag in cells and virions are largely unknown. Using crosslinking-immunoprecipitation (CLIP) sequencing, we uncover dramatic changes in the RNA binding specificity of Gag during virion genesis that are induced by its membrane binding, multimerization and proteolytic maturation. Prior to assembly, and also in mature virions, the nucleocapsid domain of Gag preferentially binds to psi and Rev Response elements in the viral genome, and GU-rich mRNA sequences. However, during assembly of immature virions, this specificity changes in a manner that facilitates genome packaging, as nucleocapsid binds to many sites on the viral genome and mRNA sequences with a similar A-rich nucleotide composition. Additionally, we find that the matrix domain of Gag binds almost exclusively to specific tRNAs in the cytosol, and this association regulates Gag binding to cellular membranes.
Project description:Single Molecule Real Time (SMRT) sequencing was utilized to map the genome-wide m6A methylation pattern in B. mayonii. Consensus modified motifs were identified in wildtype B. mayonii as well as clonal isolates lacking plasmids that encode predicted methyltransferases. Two conserved m6A modification motifs were identified, and were fully attributable to the presence of specific methyltransferases.
Project description:The plasmids introduced into the E. coli cells affect the expression of chromosomal genes. Therefore we aimed at comparing the protein expression profiles of a strain not containing any plasmid with strains that do carry plasmids.
Project description:The study aimed to characterize plasmids mediating carbepenem resistance in Klebsiella pneumoniae in Pretoria, South Africa. We analysed 56 K. pneumoniae isolates collected from academic hospital around Pretoria. Based on phenotypic and molecular results of these isolates, 6 representative isolates were chosen for further analysis using long reads sequencing platform. We observed multidrug resistant phenotype in all these isolates, including resistance to aminoglycosides, tetracycline, phenicol, fosfomycin, floroquinolones, and beta-lactams antibiotics. The blaOXA-48/181 and blaNDM-1/7 were manily the plasmid-mediated carbapenemases responsible for carbapenem resistance in the K. pneumoniae isolates in these academic hospitals. These carbapenemase genes were mainly associated with plasmid replicon groups IncF, IncL/M, IncA/C, and IncX3. This study showed plasmid-mediated carbapenemase spread of blaOXA and blaNDM genes mediated by conjugative plasmids in Pretoria hospitals.
Project description:Rhizobia are gram-negative bacteria able to establish a symbiotic interaction with leguminous plants. Due to their nitrogen fixing capacity, the study of these microorganisms has acquired great relevance for the agriculture. Rhizobia usually harbor many plasmids in their genome which can be transferred to other organisms by conjugation. Two main mechanisms of regulation of rhizobial plasmid transfer have been described: Quorum sensing (QS) and rctA/rctB system. Nevertheless, new genes and molecules that modulate conjugative transfer have been recently described, demonstrating that new actors can tightly regulate the process. In this work, by means of bioinformatics tools and molecular biology approaches, two hypothetical genes are identified as playing key roles in conjugative transfer. These genes are located between conjugative genes of plasmid pLPU83a from Rhizobium favelukesii LPU83, a plasmid that showed a conjugative transfer behavior depending on the genomic background. One of the two mentioned genes, rcgA, is essential for conjugation, while the other, rcgR, acts as an inhibitor of the process. In addition to introducing this new regulatory mechanism, we show evidence of the functions of these genes in different genomic backgrounds, and confirmed that homologous proteins from non-closely related organisms play the same function. These findings set up a cornerstone for a new molecular circuit of conjugative transfer of plasmids.