Project description:<p>Mobile colistin resistance (mcr) genes undermine the efficacy of last-line polymyxin antibiotics, and the global prevalence of mcr-3 continues to rise despite reduced colistin use. Here, we show that mcr-3-positive Escherichia coli (E. coli) confers a survival advantage by reprogramming macrophage immunity. MCR-3-mediated lipid A modification blunted TLR4-NF-kappaB signaling, suppressed macrophage reactive oxygen species (ROS) generation, and delayed phagosome-lysosome fusion, allowing mcr-3-positive strains to evade intracellular killing. Integrated transcriptomic and metabolomic analyses revealed extensive immunometabolic rewiring in infected macrophages, including altered glycerophospholipid metabolism and iron homeostasis. Consistently, mcr-3 enhanced bacterial tolerance to ferrous iron stress, likely mitigating host-induced ferroptotic damage. In a mouse co-infection model, mcr-3-positive strains outcompeted isogenic mcr-3-negative strains under antibiotic treatment without any difference in antibiotic susceptibility in vitro. These findings reveal a dual-action mechanism that mcr-3 endows E. coli with both antibiotic resistance and host immune suppression, enabling persistence under antibiotic pressure and highlighting the long-term threat of mcr-3 dissemination even in the absence of polymyxin use.</p>
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: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.
