Project description:Antibiotic resistance associated with the expression of the clinically significant carbapenemases, IMP, KPC, and NDM and OXA-48 in Enterobacteriaceae is emerging as a worldwide calamity to health care. In Australia, IMP-producing Enterobacteriaceae is the most prevalent carbapenemase-producing Enterobacteriaceae (CPE). Genomic characteristics of such carbapenemase-producing Enterobacteriaceae (CPE) are well described, but the corresponding proteome is poorly characterised. We have thus developed a method to analyse dynamic changes in the proteome of CPE under antibiotic pressure. Specifically, we have investigated the effect of meropenem at sub-lethal concentrations to develop a better understanding of how antibiotic pressure leads to resistance. Escherichia coli, producing either NDM, IMP or KPC type carbapenemase were included in this study, and their proteomes were analysed in growth conditions with or without meropenem.
Project description:We report the effect of oxygenation state in lactose grown escherichia coli producing recombinant proteins. To shed more light on the mechanistic correlation between the uptake of lactose and dissolved oxygen, a comprehensive study has been undertaken with the E. coli BL21 (DE3) strain. Differences in consumption pattern of lactose, metabolites, biomass and product formation due to aerobiosis have been investigated. Transcriptomic profiling of metabolic changes due to aerobic process and microaerobic process during protein formation phase has been studied and the results provide a deeper understanding of protein production in E. coli BL21 (DE3) strains with lactose based promoter expression systems.This study also provides a scientific understanding of escherichia coli metabolism upon oxygen fluctuations.
Project description:We investigated the in vivo and in vitro specificity of collateral RNA degradation mediated by LshCas13a protein encoded by Type VI CRISPR-Cas system derived from L. shahii. In our experimental system, we used Escherichia coli strain harboring Type VI spacer matching inducible transcript ("targeting" cells) or strain that does not encode spacers matching any E. coli transcripts ("nontargeting" cells). After the induction of the target transcription, cells were collected, total RNA samples were extracted from the cells and subjected to high throughput RNA sequencing with a specific protocol allowing to capture RNA degradation products. To investigate the influence of RNase toxins encoded in E. coli genome on the observed RNA degradation pattern, we repeated the described experiment on E. coli strain lacking ten known ribonuclease-encoding toxin-antitoxin loci. To investigate in vitro specificity of LshCas13a protein, we analyzed products of the degradation on total E. coli RNA by purified LshCas13a supplemented with crRNA and targeted or nontargeted transcripts. The obtained samples were processed as it was described above. All experiments were independently performed in triplicate. To detect transcript degradation sites, the obtained read pairs were filtered using trimmomatic tool and then mapped onto reference sequences using bowtie2. Next, for each nucleotide position of each strand of reference sequences the number of 5’ ends of aligned fragments were counted producing corresponding tables. The differences between the numbers of mapped 5’ ends in targeting and nontargeting samples were analyzed using edgeR package. Using this data, we identified target preferences for collateral RNA degradation by LshCas13a effectors.