Showcase of Undergraduate Research and Creative Endeavors (SOURCE)

Bioinformatic Analysis and Expression of Bacteriocins B and C from Xanthomonas perforans

Within the last 10 years, a new strain of the phytopathogenic bacterial genus Xanthomonas, Xanthomonas perforans, was discovered in the lesions of tomato and pepper plants. These lesions render the produce unsellable and result in a loss of profit. Prior to this discovery, Xanthomonas euvesicatoria was the primary strain that infected these types of plants and X. perforans was not found in any plants. Genomic comparisons of the two species have revealed the presence of three bacteriocin genes in X. perforans: bcnA, bcnB, and bcnC. The expression of these three bacteriocin genes enable X. perforans to outcompete X. euvesicatoria and as a result X. perforans has completely replaced X. euvesicatoria in the plant lesions. This complete replacement of one species by another is highly abnormal. Although the structures of BcnA, BcnB, and BcnC are currently unknown, homologous proteins of each bacteriocins have been identified as the wall associated protein (WapA) of Bacillus subtilis, a genus specific-serine protease, and the zinc metalloprotease of Grifola frondosa for BcnA, BcnB, and BcnC respectfully. Due to the bacterio9cin BcnA’s large size and lack of resources to express it, this project did not attempt to determine the structure of BcnA. The goal of the project was to determine the three-dimensional structure of the two smaller bacteriocins, BcnB and BcnC, and in so doing, determine the function of the proteins. To accomplish these goals, bioinformatic techniques such as homology modeling and recombinant gene expression, protein purification, and crystallization trials were used.