Project description:Although the bacterium Symbiobacterium thermophilum has a genome with a high guanine-cytosine (GC) content (69%), it belongs to a low GC content bacterial group. We detected only 18 low GC content regions with 5 or more consecutive genes whose GC contents were below 65% in the genome of this organism. S. thermophilum has 66 transposase genes, which are markers of transposable genetic elements, and 38 (58%) of them were located in the low GC content regions, suggesting that Symbiobacterium has a similar gene silencing system as Salmonella. The top hit (best match) analyses for each Symbiobacterium protein showed that putative horizontally transferred genes and vertically inherited genes are scattered across the genome. Approximately 25% of the 3338 Symbiobacterium proteins have the highest similarity with the protein of a phylogenetically distant organism. The putative horizontally transferred genes also have a high GC content, suggesting that Symbiobacterium has gained many DNA fragments from phylogenetically distant organisms during the early stage of Firmicutes evolution. After acquiring genes, Symbiobacterium increased the GC content of the horizontally transferred genes and thereby maintained a genome with a high GC content.
Project description:Neisseria meningitidis is an obligate commensal colonising the human nasopharynx and occasionally invades the bloodstream causing life-threatening meningitis and septicaemia. The gene NMB0419 on the genome of N. meningitidis MC58 encodes a putative Sel1-like repeat (SLR) containing protein, which has been implicated in mediating meningococcal invasion of epithelial cells. We prepared RNA samples from N. meningitidis MC58 (WT) and its isogenic mutant of NMB0419 grown to log phase in in-vitro culture. The RNA samples were subjected to RNA sequencing. The resulting transcriptomes were compared to determine the genes that differentially expressed in NMB0419 mutant.
