Project description:Bacterial genomes are shaped by cryptic prophages, which are viral genomes integrated into the bacterial chromosome. Escherichia coli genomes have 10 prophages on average. Though usually inactive, prophage genes can profoundly impact host cell physiology. Among the phage genes in the E. coli chromosome, there are several putative transcription factors (TFs). These prophage TFs are predicted to control only phage promoters, however their regulatory functions are not well characterized. The co-habitation of prophages and bacteria has led to conditions under which the majority of prophage genes are unexpressed, at least under normal growth conditions. We characterized a Rac prophage TF, YdaT, expression of which is normally inhibited by Rac TFs and, surprisingly, by the host global regulator OxyR. YdaT, when expressed, leads to a toxic phenotype manifested by drastic cell filamentation and cell death. We determined the binding sites and regulatory action for YdaT, finding two sites within the Rac locus, and one upstream of the host rcsA gene, which codes for the global regulator RcsA. The resulting increase in RcsA strongly impacts the bacterial RcsA/B regulon, which includes operons related to motility, capsule biosynthesis, colanic acid production, biofilm formation and cell division. Our results provide novel insights into the host’s genetic network, which appears to integrate YdaT in a complex manner, favoring its maintenance in the silenced state. The fact that the potentially-toxic YdaT locus remains unmutated suggests its importance and potential benefits for the host, which may appear under stress conditions that are not yet known.
Project description:An experiment to identify the downstream targets of PatE, a prophage encoded AraC-like transcriptional regulator, in transcriptional activation of acid-resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 using deletion and complementation strains (Delta3 and Delta3_1, respectively).
Project description:The goal of this study is to seek the potential circular RNAs (circRNAs), which express differently between control group and chronic unpredictable stress (CUS) group mouse hippocampus, involved in major dipresssion disorder (MDD) by high-throughput sequencing. QPCR was preformed to identify the circRNAs trend. CircRNAs are a class of RNAs in the eukaryotic transcriptome. The function and explicit downstream mechanisms of circRNA regulated in maior depression disorser remain unclear. To further investigate the potential role of circRNAs in MDD, we performed human and mouse homology screening on circRNA sequences using the Basic Local Alignment Search Tool on the NCBI website. CircSTAG1, a homologous human and mouse circRNA, was found downregulated in circRNA high-throughput sequencing. Our study represents the first detailed analysis of circRNA expressing differently in CUS mouse hippocampus by high-throughput sequencing.
Project description:After the attachment of the lytic phage T4 to Escherichia coli cells, 1% E. coli cells showed an approximately 40-fold increase in mutant frequency. They were designated as mutator A global transcriptome analysis using microarrays was conducted to determine the difference between parental strain and mutators.
Project description:Total proteome analysis of CP4-57 prophage- and ssrA-related variants in Escherichia coli. Quantification was performed by SWATH-MS method.
