|ELDER, JACOB - Washington State University|
|NARAYAN, PAUL - Washington State University|
|BURIN, RAQUEL - Washington State University|
|SHAH, DEVENDRA - Washington State University|
Submitted to: International Journal of Medical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2018
Publication Date: 12/20/2018
Citation: Elder, J.R., Narayan, P., Burin, R., Guard, J.Y., Shah, D.H. 2018. Genomic organization and role of SPI-13 in nutritional fitness of Salmonella. International Journal of Medical Microbiology. 308(8):1043-1052
Interpretive Summary: Salmonella pathogenicity island 13 (SPI-13) contributes to the virulence of Salmonella. The majority of the SPI-13 genes encode proteins putatively involved in bacterial metabolism, however their functions largely remain uncharacterized. It is currently unknown if SPI-13 contributes to metabolic fitness of Salmonella and, if so, what are the metabolic substrates for the protein encoded by genes within SPI-13. We employed Phenotype Microarray (Biolog, USA) to compare the metabolic properties of SPI-13 deficient mutant ('SPI-13) and the WT parent strain of nontyphoidal Salmonella enterica sub sp. enterica serovar Enteritidis (S. Enteritidis). The results of Phenotype Microarray revealed that SPI-13 is required for efficient utilization of two micronutrients, namely, D-glucuronic acid (DGA) and tyramine (TYR), as sole sources of carbon and/or nitrogen. By systematic deletion of individual gene(s), we identified specific genes within SPI-13 that are required for efficient utilization of DGA (SEN2977-80) and TYR (SEN2967 and SEN2971-72) as sole nutrient sources. The results show that SPI-13 mediated DGA and TYR metabolic pathways afford nutritional fitness to S. Enteritidis. Comparative genomics analysis of the SPI-13 locus from 247 Salmonella strains belonging to 57 different serovars revealed that SPI-13 genes specifically involved in the metabolism of DGA and TYR are highly conserved in Salmonella enterica. Because DGA and TYR occur in abundance in the gastrointestinal tract and other host tissues, we propose a metabolic model that shows that the role of SPI-13 mediated DGA and TYR metabolism in nutritional fitness of Salmonella is likely linked to nutritional virulence of this pathogen.
Technical Abstract: It is difficult to tell which compounds in the environment of poultry are used by pathogenic bacteria as a source of energy during the infection pathway that results in foodborne illness in people. This research demonstrates that the genomic region known as pathogenicity island SPI-13 of Salmonella enterica serovar Enteritidis is essential for using D-glucuronic acid and Tyramine as sole sources of carbon and/or nitrogen. Thus SPI-13 ensures nutritional fitness of one of the most important serotypes causing salmonellosis in people.