Genome of Renibacterium salmoninarum
Renibacterium salmoninarum, a gram-positive bacterium, is the causative agent of bacterial kidney disease (BKD) in salmon. Bacterial kidney disease is characterized by lesions of the kidney and has a very high mortality rate. It occurs worldwide among wild and commercially raised fish populations, as well as in captive broodstocks of endangered species. Currently there are no effective preventative treatments. The aim of the project was to sequence the R. salmoninarum genome and use this data to identify targets for novel treatments that will help us prevent this disease.
In the processes of analyzing and annotating over 1,400 potential genes, I characterized several classes of genes that are especially promising targets for future treatments, including: macrolide and multidrug secretion proteins (an antibiotic resistance mechanism), signal peptide containing proteins (the targeting signal for attachment to the cell wall), and a sortase enzyme (responsible for the covalent attachment of surface exposed proteins to the cell wall). I discovered an intact sortase enzyme and successfully identified all of the genes that potentially encode sortase substrate proteins.
My findings were used to identify upregulated genes in antibiotic resistant strains of the bacterium, shown in the immunofluorescence image to the right (Ponnerassery et al. 2007). This is the first step towards the development of novel treatments that may result in the abatement of bacterial kidney disease. Such a development will have significant impacts on commercial fisheries and salmon conservation programs.