Project description:Gene regulation is one of the most ubiquitous processes in biology. And yet, while the catalogue of 15 bacterial genomes continues to expand rapidly, we remain ignorant about how almost all of the genes in 16 these genomes are regulated. Characterizing the molecular mechanisms by which regulatory sequences 17 operate still requires focused efforts using low-throughput methods. Here we show how a combination of 18 massively parallel reporter assays, mass spectrometry, and information-theoretic modeling can be used 19 to dissect bacterial promoters in a systematic and scalable way. We demonstrate this method on both 20 well-studied and previously uncharacterized promoters in the enteric bacterium Escherichia coli. In all 21 cases we recover nucleotide-resolution models of promoter mechanism. For some promoters, including 22 previously unannotated ones, we can further extract quantitative biophysical models describing 23 input-output relationships. This method opens up the possibility of exhaustively dissecting the 24 mechanisms of promoter function in E. coli and a wide range of other bacteria.
Project description:N4-methylcytosine is a major DNA modification integral to restriction-modification (R-M) systems in bacterial genomes. Here we describe 4mC-Tet-Assisted Bisulfite-sequencing (4mC-TAB-seq), a method that accurately and rapidly reveals the genome-wide locations of N4-methylcytosines at single-base resolution. By coupling Tet-mediated oxidation with a modified sodium bisulfite conversion reaction, unmodified cytosines and 5-methylcytosines are read out as thymines, whereas N4-methylcytosines are read out as cytosines revealing their positions throughout the genome. 4mC-TAB-seq
Project description:To determine the optimal RNA-Seq approach for animal host-bacterial symbiont analysis, we compared transcriptome bias, depth and coverage achieved by two different mRNA capture and sequencing strategies applied to the marine demosponge Amphimedon queenslandica holobiont, for which genomes of the animal host and three most abundant bacterial symbionts are available.
Project description:Full title: Probing the pan genome of a foodborne bacterial pathogen Listeria monocytogenes: Implications for its niche adaptation, pathogenesis, and evolution Listeria monocytogenes is a foodborne bacterial pathogen well known for adaptability to diverse environmental and host niches, and a high fatality rate among infected, immuno-compromised individuals. Three genetic lineages have been identified within this species. Strains of genetic lineages I and II account for more than ninety percent of foodborne disease outbreaks worldwide, whereas strains from genetic lineage III are rarely implicated in human infectious for unknown, yet intriguing, reasons. Here we have probed the genomic diversity of 26 L. monocytogenes strains using both whole-genome sequences and a novel 385,000 probe pan-genome microarray, fully tiling the genomes of 20 representative strains. Using these methods to identify genes highly conserved in lineages I and II but rare in lineage III, we have identified 86 genes and 8 small RNAs that play roles in bacterial stress resistance, pathogenicity, and niche, potentially explaining the predominance of L. monocytogenes lineages I and II in foodborne disease outbreaks. Extending gene content analysis to all lineages revealed a L. monocytogenes core genome of approximately 2,350 genes (80% of each individual genome) and a pan-genomic reservoir of >4,000 unique genes. Combined gene content data from both sequences and arrays was used to reconstruct an informative phylogeny for the L. monocytogenes species that confirms three distinct lineages and describes the relationship of 9 new lineage III genomes. Comparative analysis of 18 fully sequenced L. monocytogenes lineage I and II genomes shows a high level of genomic conservation and synteny, indicative of a closed pan-genome, with moderate domain shuffling and sequence drift associated with bacteriophages is present in all lineages. In contrast with lineages I and II, notable genomic diversity and characteristics of an open pan-genome were observed in the lineage III genomes, including many strain-specific genes and a more complex conservation pattern. This indicates that the L. monocytogenes pan-genome has not yet been fully sampled by genome sequencing, and additional sequencing of lineage III genomes is necessary to survey the full diversity of this intriguing species and reveal its mechanisms for adaptability and virulence.