Project description:Purpose: We use the gene expression data to estimate the effects of tetracycline on gene expression and average ribosome density. Methods: The mRNAs were extracted with TRIzol reagent. The mRNAs were fragmented into 280 bp and the sequencing process was conducted on HiSeq 2500 platform. We use cutadapt, bowtie2, Plastid and DEseq2 software to analyze the expression levels of genes in two Escherichia coli strains. Results: The gene expression in EF4 knockout Escherichia coli strain was similar with BW25113 strain under normal condition. Under tetracycline treatment, many genes' expression were differentially regulated. Interestingly, we found that the gene expression of ribosomal proteins was up-regulated in WT strain comparing with EF4 knockout E. coli strain. Conclusions: Our results suggest that EF4 affects the average ribosome density and global gene expression in two Escherichia coli strain under tetracycline treatment.
Project description:RpoS, an alternative sigma factor, is critical for stress response in Escherichia coli.RpoS also acts as a global regulator for stress control of gene expression, and actually dose so in log stage and stationary stage. To further understand the effect of environmental stresses on in ethanologenic strains, DNA microarrys was used to analyze the expression profiles of E. coli and its rpoS mutant strain.
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:Glycerol is an attractive feedstock for biofuels since it accumulates as a byproduct during biodiesel operations; hence, it is interesting to consider converting glycerol to hydrogen using the formate hydrogen lyase system of Escherichia coli which converts pyruvate to hydrogen. Starting with Escherichia coli BW25113 frdC that lacks fumarate reductase to eliminate the negative effect of accumulated hydrogen on glycerol fermentation and by using both adaptive evolution and chemical mutagenesis combined with a selection method based on increased growth on glycerol, we obtained an improved strain, HW2, that produces 20-fold more hydrogen in glycerol medium (0.68 mmol/L/h) compared to that of frdC mutant. HW2 also grows 5-fold faster (0.25 1/h) than BW25113 frdC on glycerol, so it achieves a reasonable growth rate. Corroborating the increase in hydrogen production, glycerol dehydrogenase activity in HW2 increased 4-fold compared to BW25113 frdC. In addition, a whole-transcriptome study revealed that several pathways that would decrease hydrogen yields were repressed in HW2 (fbp, focA, and gatYZ) while a beneficial pathway, eno which encodes enolase was induced.
Project description:The impact of 2',3'-cyclic nucleotide phosphodiesterase (CNPase) on global gene expression in E. coli was investigated by heterologous expression of mammalian CNPase in a strain containing a deletion of the 'rna' gene. 'rna' encodes an endoribonuclease capable of hydrolyzing RNA into 2',3'-cyclic nucleotide monophosphates (2',3'-cNMPs) such that deletion of 'rna' drastically reduces 2',3'-cNMPs levels to undetectable levels. Expression of CNPase in this strain allowed any effects of CNPase unrelated to 2',3'-cNMPs to be observed.
Project description:We replaced the natural pnp locus with the human cDNA and studied the transcriptomes of 3 strains, namely the wt pnp+ (C-1a), the mutant with pnp ORF deletion (C-5691) and the strain with the substitution of the bacterial ORF with the human one (C-6001).