Project description:Purpose: We use the ribosome profiling protocol to understand why EF4 confers resistance to tellurite and how tellurite affects ribosome. Methods: We used ribosome profiling and transcriptomic data to analyze mainly by plastid software. The ribosome were purified by sucrose gradient separation. Results: Using polysome profile and sequencing data, we found that tellurite disables the ribosome subunits to form a functional 70S ribosome and reduces the ribosome density after tellurite exposure. We also found that tellurite influences the ribosome reaching to stop codon. Tellurite shortened the ribosome protected fragment, this process was mediated by EF4. EF4 mediated more gene expression including these known tellurite resistance genes to confer tellurite resistance. Tellurite also induced many differential gene expression. Conclusions: Tellurite exerts its toxicity on ribosome by disabling 70S ribosome formation, reaching to stop codon, and inducing differential gene expression.
Project description:Transcriptional profiling comparing Escherichia coli simultaneously exposed to tellurite and CTX with untreated control cells; Tellurite with control; CTX with control Three-condition experiment, antibacterial (tellurite; CTX or tellurite/CTX) vs. Untreated control cells. Biological replicates: 3 control, 3 toxicants exposed cells, independently grown and harvested. One replicate per array.
Project description:Transcriptional profiling comparing Escherichia coli simultaneously exposed to tellurite and CTX with untreated control cells; Tellurite with control; CTX with control
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.
Project description:Escherichia coli (E. coli) amine oxidase (ECAO) encoded by tynA gene has been one of the model enzymes to study the mechanism of oxidative deamination of amines to the corresponding aldehydes by amine oxidases. The biological roles of ECAO have been less addressed. Therefore we have constructed a gene deletion Escherichia coli K-12 strain, E. coli tynA-, and used the microarray technique to address its function by comparing the total RNA gene expression to the one of the wt. Our results suggest that tynA is a reserve gene for stringent environmental conditions and its gene product ECAO a growth advantage compared to other bacteria due to H2O2 production.
Project description:Successful pathogens must be able to protect themselves against reactive nitrogen species generated either as part of host defence mechanisms, or as products of their own metabolism. The regulatory protein, NsrR (a member of the Rrf2 family of transcription factors), plays key roles in this stress response. Microarray analysis was carried out to reveal the regulon of NsrR. Keywords: Response to repressor titration and different growth conditions