Title: Phylogenetic identification of bacterial MazF toxin protein motifs among probiotic strains and foodborne pathogens and potential implications of engineered probiotic intervention in food Authors
Submitted to: BioMed Central(BMC) Cell & Bioscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2012
Publication Date: November 27, 2012
Repository URL: http://handle.nal.usda.gov/10113/57661
Citation: Yan, X., Gurtler, J., Fratamico, P.M., Hu, J., Juneja, V.K. 2012. Phylogenetic identification of bacterial MazF toxin protein motifs among probiotic strains and foodborne pathogens and potential implications of engineered probiotic intervention in food. BioMed Central(BMC) Cell & Bioscience. 2:39. Interpretive Summary: The term probiotics refers to live bacteria that are beneficial to health and are used as dietary supplements and also can found in food such as yogurt. Some probiotics have been shown to suppress the growth of harmful bacteria in the gastrointestinal tract, and some produce antimicrobial compounds that can inactivate pathogens. There are two approaches that can be used to enhance the effectiveness of probiotics. One approach is to use a combination of different probiotic strains that can target specific pathogens, and another approach is to genetically engineer probiotic bacteria to inactivate pathogens. Food-borne diseases continue to be an important public health concern in developing, as well as in developed countries, thus prevention of food-borne illness through effective and novel interventions is critical. Furthermore, overuse of antibiotics in humans and animals has contributed to the development of multi-antibiotic-resistant food-borne pathogens. The research reported provides genetic engineering approaches that can be used to create probiotic strains that can inactivate specific food-borne pathogens through the production of antimicrobial peptides or proteins. The genomic (total genetic content of an organism) DNA sequences currently available for probiotic bacteria and food-borne pathogens in public databases were aligned to identify genes that could be employed to genetically engineer the probiotic bacteria and to determine which probiotics could potentially be combined in specific cocktails of strains to inactivate specific pathogens. These computational modeling approaches represent a first attempt to describe systematic methods to test the hypothesis that “friendly” bacteria can be used to inactivate or inhibit pathogens in food, and potentially in animals and humans.
Technical Abstract: The most common mechanism involved in bacterial programmed cell death or apoptosis is through toxin-antitoxin (TA) modules, which exist in many bacterial species. An experimental procedure or method that provides novel insights into the molecular basis for the development of engineered/synthetic probiotic strains for the mitigation of food-borne illnesses is described. It consists of an integrated approach combining phylogenetic analyses and molecular recombination bio-techniques to investigate one of most well-studied bacterial toxin-antitoxin modules (mazEF), encoding for MazF, a cell growth regulatory protein/growth inhibitor present in probiotic strains and major food-borne pathogens. Our findings show that some probiotic strains, as well as many bacterial food-borne pathogens can be genetically categorized into several groups based on two different proteins: MazF, the toxin component of the toxin-antitoxin module; and the beta-subunit of the DNA-directed RNA polymerase, RpoB. The genomic sequences and gene annotation information of these two proteins were obtained from the National Center for Biotechnology Information (NCBI) public database. The representative sequences from diverse species were aligned using ClustalW and in a PHYLIP format to generate a multiple sequence alignment file for the construction of phylogenetic trees. Based on the computational phylogenetic tree analysis of these multiple protein sequences and in-depth data mining of the probiotic literature, we concluded that it is possible to develop various synthetic probiotic strains engineered by genetic transformation via chromosomal integration or plasmid transformation with a recombinant secreted fusion MazF protein and a small extracellular cell death factor (CDF) or to use a natural probiotic cocktail to potentially control specific food-borne pathogens.