Project description:Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is a Gram-negative pathogen that must successfully adapt to the broad fluctuations in the concentration of dissolved dioxygen encountered in the host. In Escherichia coli, ArcA (Aerobic Respiratory Control) helps the cells to sense and respond to the presence of dioxygen. The global role of ArcA in E. coli is well characterized; however, little is known about its role in anaerobically grown S. Typhimurium. Results: We compared the transcriptional profiles of the virulent wild-type (WT) strain (ATCC 14028s) and its isogenic arcA mutant grown under anaerobic conditions. We found that ArcA directly or indirectly regulates 392 genes (8.5% of the genome); of these, 138 genes are poorly characterized. Regulation by ArcA in S. Typhimurium is similar, but distinct from that in E. coli. Thus, genes/operons involved in core metabolic pathways (e.g., succinyl-CoA, fatty acid degradation, cytochrome oxidase complexes, flagellar biosynthesis, motility, and chemotaxis) were regulated similarly in the two organisms. However, genes/operons present in both organisms, but regulated differently by ArcA in S. Typhimurium included those coding for ethanolamine utilization, lactate transport and metabolism, and succinate dehydrogenases. Salmonella-specific genes/operons regulated by ArcA included those required for propanediol utilization, flagellar genes (mcpAC, cheV), Gifsy-1 prophage genes, and a few SPI-3 genes (mgtBC, slsA, STM3784). In agreement with our microarray data, the arcA mutant was non-motile, lacked flagella, and was as virulent in mice as the WT. Furthermore, we identified a set of 120 genes whose regulation was shared with the anaerobic redox regulator, Fnr. Conclusion(s): We have identified the ArcA regulon in anaerobically grown S. Typhimurium. Our results demonstrated that in S. Typhimurium, ArcA serves as a transcriptional regulator coordinating cellular metabolism, flagella biosynthesis, and motility. Furthermore, ArcA and Fnr share in the regulation of 120 S. Typhimurium genes.
Project description:Mapping the occupancy of ArcA throughout the genome of Escherchia coli MG1655 K-12 using an affinity purified antibody under anaerobic and aerobic growth conditions. As a control, we also performed ChIP-chip onArcA in a ∆arcA mutant strain of Escherchia coli MG1655 K-12. Described in the manuscript The response regulator ArcA uses a diverse binding site architechture to globally regulate carbon oxidation in E. coli
Project description:Purpose:The oxygen-regulated genes FNR and ARCA were combined with Komagataeibacter xylinus CGMCC 2955 to provide a new perspective for the study of the mechanism of oxygen environment on BC synthesis. Methods:The FNR and Arca overexpressing strains and the control strains were fermented under different partial oxygen pressures. The bacterial cellulose membrane in the logarithmic period of fermentation was enzymolyzed, and the bacteria were collected for transcriptome analysis.Sequencing was performed with Illumina and transcriptome analysis was performed on the bacteria under different conditions. Results:Transcriptome sequencing was performed using Illumina high-throughput sequencing technology on K. xylinus cultured under different oxygen tensions. The differentially expressed genes in the arcA overexpressing strains were mainly in the sulfur metabolism, two-component system, purine metabolism, and amino acid metabolism pathways compared to the control strains. Analysis showed that the arcA overexpression strain activated the sulfur metabolic pathway in K. xylinus. Due to the insufficient oxygen electron acceptors in the hypoxia, sulfate acted as the final electron acceptor and enhanced the growth ability of the strain. Through global regulation of the pathways of bacterial growth and metabolism as well as BC synthesis under low oxygen conditions, the arcA gene has enabled the strain to reach new levels of BC production. This study lays the foundation for further investigation of the mechanism of the effect of oxygen on BC synthesis in K. xylinus.