Project description:Violacein, a bisindole derivative produced, among others, by bacteria of the genus Janthinobacterium and Chromobacterium, is a compound with proven antimicrobial, anticancer and immunomodulatory properties. The anti-cancer activity of violacein has been tested on many cancer cells, including lung cancer cells, colorectal adenoma cells, acute myeloid leukaemia cells and melanoma cells. Interestingly, in a mouse model, a large difference in the response of cancerous and non-cancerous cells to violacein was observed, further highlighting the therapeutic potential of this compound. In addition, violacein has been observed to reduce the invasive potential of melanoma cells and has a much more potent anticancer effect than temozolomide, a drug used to treat melanoma. Violacein can be isolated from the bacterial cell pellet using solvents, and this metabolite is also secreted into the medium in a form enclosed in extracellular vesicles (EVs), in which the normally insoluble violacein remains suspended in water. The project focuses on the development of an efficient method of violacein application based on the use of EVs. Violacein-containing EVs were isolated from the culture of Janthinobacterium sp. and characterised by their appearance, size and protein composition. The activity of isolated EVs containing violacein was compared with the activity of violacein traditionally isolated from cells using solvents against four skin cell lines (cancerous and non-cancerous)
Project description:Violacein, an indole-derived purple-colored natural pigment isolated from Chromobacterium violaceum has shown multiple biological activities. In this study, we report that violacein activates murine macrophages through the up-regulation of TNF-α expression at non-cytotoxic concentrations (2 µmol/L). This was evaluated by measurement of TNF-α expression using real-time qRT-PCR. In addition, we obtained evidence of the molecular mechanism of activation by determining the mRNA expression pattern upon treatment with violacein. Interestingly, the mRNA expression pattern also allowed us to observe that incubation with violacein caused activation of pathways related with an immune and inflammatory response. Together, our data indicate that violacein activates the TLR8 receptor signaling pathway, and in consequence induces production of inflammatory cytokines such as TNF-α, CCL3 and CCL4 and of negative regulators of TLR signaling such as AP20, IRG1, IκBα and IκBε. Finally, we studied the interaction of TLR8 with violacein in silico, and obtained evidence that violacein could bind to TLR8 in a similar fashion to imidazoquinoline compounds. Therefore, our results indicate that violacein could be a candidate to be applied in immune therapy.
Project description:Members of the genus Chromobacterium have been isolated from geographically diverse ecosystems and exhibit considerable metabolic flexibility, as well as biotechnological and pathogenic properties in some species. This study reports the draft assembly and detailed sequence analysis of Chromobacterium amazonense strain 56AF. The de novo-assembled genome is 4,556,707 bp in size and contains 4294 protein-coding and 95 RNA genes, including 88 tRNA, six rRNA, and one tmRNA operon. A repertoire of genes implicated in virulence, for example, hemolysin, hemolytic enterotoxins, colicin V, lytic proteins, and Nudix hydrolases, is present. The genome also contains a collection of genes of biotechnological interest, including esterases, lipase, auxins, chitinases, phytoene synthase and phytoene desaturase, polyhydroxyalkanoates, violacein, plastocyanin/azurin, and detoxifying compounds. Importantly, unlike other Chromobacterium species, the 56AF genome contains genes for pore-forming toxin alpha-hemolysin, a type IV secretion system, among others. The analysis of the C. amazonense strain 56AF genome reveals the versatility, adaptability, and biotechnological potential of this bacterium. This study provides molecular information that may pave the way for further comparative genomics and functional studies involving Chromobacterium-related isolates and improves our understanding of the global genomic diversity of Chromobacterium species.