Project description:The heat shock response is critical for organisms to survive at a high temperature. Heterologous expression of eukaryotic molecular chaperons protects Escherichia coli against heat stress. Here we report that expression of the plant E3 ligase BnTR1 significantly increase the thermotolerance of Escherichia coli. Different from eukaryotic chaperones, BnTR1 post-transcriptionally regulates the heat shock factor σ32 though zinc fingers of the RING domain, which interacts with DnaK resulting in stabilizing σ32 and subsequently up-regulating heat shock proteins. Our findings indicate the expression of BnTR1 confers thermoprotective effects on E. coli cells, and it may provide useful clues to engineer thermophilic bacterial strains.
Project description:The locus of heat resistance (LHR) confers extreme heat resistance in E. coli. This study explored the role of the LHR in pressure resistance of E. coli, as well as its relationship with protein folding and aggregation in vivo. The role of LHR was investigated in E. coli MG1655 expressing a ibpA-yfp fusion. The expression of proteins by the LHR was determined by mass spectrometry based proteomics; inclusion bodies of untreated and treated cells were also analysed by proteomics, and by observation with fluorescence microscope. In total, 11 proteins of LHR were expressed, including sHSP20, ClpKGI, sHSP, YdfX1 and YdfX2, HdeD, KefB, Trx, PsiE, DegP, and a hypothetical proteins. The proteomic analysis of inclusion bodies revealed a differential abundance of proteins related to oxidative stress in strains carrying the LHR. The LHR reduced the presence of inclusion bodies after heat or pressure treatment, indicating that proteins expressed by the LHR prevent or reverse protein aggregation. The phenotype of the LHR was also mediated by the expression of a fragment containing only sHSP20, ClpKGI, sHSP. The LHR and the fragment encoding only for sHSP20, ClpKGI, sHSP also enhanced pressure resistance in E. coli MG1655 but had no effect on pressure resistance of E. coli LMM1010. In conclusion, the LHR confers pressure resistance to some strains of E. coli, and reduces protein aggregation. Pressure and heat resistance, however, are also dependent on additional LHR-encoded functions.
Project description:The aim of this study was to investigate the expressional changes profiles of the wildtype and recombinant Escherichia coli strain which contains an non-coding RNA nfiS from the nitrogen-fixing Pseudomonas stutzeri A1501 after hydrogen peroxide shock, so as to lay a theoretical foundation for further clarifying the mechanism of this ncRNA to enhance the resistance ability of E.coli to oxidative stress. In our early research, an ncRNA named NfiS from the nitrogen fixing bacteria Pseudomonas stutzeri A1501 was identified to play an important role in the response to oxidative as well as osmotic stress. In this work, the nifS gene was transferred to E. coli Trans10. Heterologous expression of the nfiS in Trans10 enhanced its tolerance to salt stress and oxidative stress. To further study the effect of nfiS on gene expression in E. coli, microarray assay was performed to delineate the transcriptome difference between nfiS-expressing strain and wild type under H2O2 shock treatment.
Project description:Heterologous gene expression to expand the native genetic capability of E. coli is the backbone of protein expression and metabolic engineering. The goal of this study was to determine how the identity of the heterologous gene expressed affected the host cell transcriptome. We generated a library of E. coli expressing 46 heterologous genes through an identical rhamnose inducible expression system and perform high throughput ribosome profiling.
Project description:The OsMyb4 transcription factor of rice represents a more recent example of a regulatory gene used in various attempts to develop stress-tolerant crops by regulon engineering. Although OsMyb4 confers tolerance to low temperature and drought by affecting the biosynthesis of compatible osmolytes and the phenylpropanoid metabolic process, the exact composition and scope of the OsMyb4 network has not been established from the previous analysis of heterologous overexpression in Arabidopsis. Further characterization of the OsMyb4 regulon at the global scale will facilitate understanding of the intricate underpinnings of a pathway independent of the DREB/CBF network. To dissect the OsMyb4 network of rice in relation to chilling stress response mechanisms, we conducted a gene expression profiling using transgenic rice overexpressing the OsMyb4 cDNA.
Project description:Heterologous gene expression to expand the native genetic capability of E. coli is the backbone of protein expression and metabolic engineering. The goal of this study was to determine how the identity of the heterologous gene expressed affected the host cell transcriptome. We generated a library of E. coli expressing 46 heterologous genes through an identical rhamnose inducible expression system and perform high throughput RNAseq as well as independent component analysis to elucidate the major variances in the transcriptome. We find that the major variations during heterologous gene expression can be divided into 5 main cellular responses: Fear vs greed, metal homeostasis, respiration, protein folding and amino acid and nucleotide metabolism.
Project description:Escherichia coli laboratory strains remain instrumental to the discovery and development of biomarkers as drugs and diagnostic analytes in the post genomic era. The transcriptional regulator SlyA is a member of the multiple antibiotic resistance regulator family of transcription factors, which is associated with bacterial responses to host-derived oxidative stress, antibiotics resistance and virulence, and homologues exist in other Enterobacteriaceae. Here, we announce a transcriptome RNA sequencing data set detailing global gene expression in the wild type E. coli BW25113 and the slyA mutant. Results reveal heterogeneous functionality of SlyA that may vary between pathovars of E. coli. but which require further annotations of differentially expressed tRNAs
Project description:Housekeeping sigma factors in the Sigma70 family, as components of the RNA polymerase holoenzyme, are responsible for regulating transcription of genes related to vegetative growth. While these factors are well understood in model organisms such as Escherchia coli and Bacillus subtilis, little experimental work has focused on the sigma factors in members of the Lactobacillus genus such as Lactobacillus brevis and Lactobacillus plantarum. This study evaluates the ability of putative Sigma70 proteins from L. brevis (Sigma70-Lb) and L. plantarum (Sigma70-Lp) to complement a temperature sensitive mutation in E. coli 285c Sigma70. After finding that the heterologous sigma factors were capable of restoring the viability of E. coli 285c at 42 C through growth kinetics studies, the transcriptional responses of 285c to an extended heat shock in the presence of Sigma70-Lb and Sigma70-Lp were found to be similar to previous studies. These results indicate the Sigma70-Lb and Sigma70-Lp are capable of initiating transcription in a complex with the E. coli 285c RNA polymerase to a sufficient degree to restore viability at elevated temperatures without triggering unusual modifications to the native transcriptional program. These heterologous sigma factors may therefore be useful to improve biochemical knowledge of the sigma factor family or for use in transcriptional engineering.
Project description:There is increasing evidence to support a role for sigma factor 54 (RpoN) in the regulation of stress resistance factors and protein secretion systems important to bacterial transmission and pathogenesis. In enterohemorrhagic E. coli O157:H7, acid resistance and type III secretion are essential determinants of gastric passage and colonization. This study thus described the transcriptome of an rpoN null strain of E. coli O157:H7 (EcJR-8) to determine the influence of RpoN on virulence and stress resistance gene regulation, and further explored its contribution to glutamate-dependent acid resistance (GDAR). Inactivation of rpoN resulted in the growth phase-dependent, differential expression of 104 genes. This included type III secretion structural and regulatory genes encoded on the locus of enterocyte effacement (LEE), as well as GDAR genes gadA, gadBC and gadE. Upregulation of gad transcript levels in EcJR-8 during logarithmic growth correlated with increased GDAR and survival in a model stomach. Acid susceptibility was reconstituted in EcJR-8 complemented in trans with wild-type rpoN. Acid resistance in EcJR-8 was dependent on exogenous glutamate, gadE and rpoS, but was independent of hns. Results also suggest that GDAR may be controlled by RpoN at multiple regulatory levels. This study supports the hypothesis that RpoN is an important regulator of virulence and stress resistance factors in E. coli O157:H7, and is the first to examine the mechanism by which it represses GDAR. Hybridizations measured transcriptional differences between an rpoN null and wild-type (WT) strain of E. coli O157:H7 Sakai at logarithmic and transition phase. Image files (TIFF) of hybridized microarray slides were generated using an Axon 4000B scanner (Molecular Devices), and analyzed using GenePix Pro software (Molecular Devices, ver. 6.0). The resulting microarray intensity data was log2-transformed, and normalized using the LOWESS algorithm in MAANOVA ver. 0.98-8 (R ver. 2.2.1).
Project description:YbjN, an enterobacteria-specific protein, is a multicopy suppressor of ts9 temperature sensitivity in Escherichia coli. Microarray study revealed that the expression level of ybjN was inversely correlated with the expression of flagellar, fimbrial and acid resistance genes. Over-expression of ybjN significantly down-regulated genes involved in the citric acid cycle, glycolysis, the glyoxylate shunt, oxidative phosphorylation, and amino acid and nucleotide metabolism. On the other hand, over-expression of ybjN up-regulated toxin-antitoxin modules, the SOS responsive pathway, cold shock proteins and starvation-induced transporter genes. Our results collectively suggest that YbjN may play important roles in regulating bacterial multicellular behaviors, metabolism and survival under various stress conditions in Es. coli. A total of 8 samples were analyzed: E. coli wild type strain (2 replicates); E. coli ybjN mutant strain (3 replicates); E. coli ybjN over-expression strain (3 replicates).