yeast-based genetic screen for identification of pathogenic Salmonella proteins

• Published in: FEMS microbiology letters 2009-07, Vol.296 (2), p.167-177
• Main Authors: Alemán, Ainel, Fernández-Piñar, Pablo, Pérez-Núñez, Daniel, Rotger, Rafael, Martín, Humberto, Molina, María
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - toxicity; Bacteriological methods and techniques used in bacteriology; Bacteriology; Biological and medical sciences; Cell proliferation; Chromosomes; Cytoskeleton; Cytoskeleton - drug effects; Effectors; Eukaryotes; Fundamental and applied biological sciences. Psychology; Gene Expression; Genes; Genetic screening; Horizontal transfer; Internalization; Mammalian cells; Microbiology; Pathogenesis; pathogenic protein; Pathogens; Proteins; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Salmonella; Salmonella typhi - genetics; Salmonella typhimurium - chemistry; Salmonella typhimurium - genetics; Salmonella typhimurium - pathogenicity; Secretion; Toxicity; Transformation, Genetic; TTSS effectors; Virulence; Virulence Factors - genetics; Virulence Factors - toxicity; Yeast; Yeasts
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2009.01630.x

Salmonella uses type III secretion systems (TTSS) to deliver pathogenic proteins into the host cells. These translocated effectors induce bacterial internalization and intracellular proliferation by targeting important cellular processes that are conserved among eukaryotes. Here, we assessed the feasibility of performing a genetic screen in yeast to identify novel Salmonella effectors, by searching for genes that produce toxicity when expressed in this model system. We identified several known TTSS-translocated effectors and found that two of them, SteC and SseF, from Salmonella enterica serovar Typhimurium, interfere with cytoskeletal dynamics as they do in mammalian cells. We also identified 11 genes of unknown function (seven from S. Typhi and four from S. Typhimurium) that display features commonly showed by effector proteins, such as a (G+C) content lower than the average for the chromosome, suggesting their acquisition by horizontal transfer processes. Five of these proteins are highly conserved only among Salmonella serovars, whereas the other six are also conserved in other pathogenic or opportunistic enterobacteria. Moreover, we identified other proteins that share specific activity domains with either translocated or bacterial-confined proteins known to be involved in pathogenesis, which might also act as virulence proteins.