Investigating the cytotoxic effects of mycobacteriophage Vix Gene 80

Abstract

A bacteriophage is a virus that infects and replicates in bacteria. To reproduce, the phage must convert the host cell metabolism from that suited for cell survival to one favorable for producing new phage progeny. One mechanism by which phage can cause host cell conversion is by expressing ‘cytotoxic’ phage gene products that interact with and inhibit the function of specific protein targets of key metabolic pathways of the bacterial host. Identifying ‘cytotoxic’ phage genes and understanding more about how phage exploit their host's weaknesses could lead to new and important therapies for many bacterial illnesses. In this work, a cytotoxic gene from mycobacteriophage Vix, gene 80, was studied. The protein of the Vix80 gene is 68% identical to the product of gene 77 of mycobacteriophage L5, a gene that has been shown to be cytotoxic to Mycobacterium. We confirmed that the Vix80 gene product is also cytotoxic when expressed in Mycobacterium smegmatis. Our hypothesis is that a physical interaction between the Vix80 gene product and a specific host cell protein affects cell metabolism and causes growth inhibition. A 6xHis tagged Vix80 protein was created and expressed in E. coli, and then purified by column chromatography. SDS‐PAGE and staining verified that we had expressed and purified the Vix80 protein of correct size. We are using the His‐tagged Vix80 protein in a biochemical approach to identify the interacting host cell protein. Supported by an ASBMB Undergraduate Research Award, and a Summer Research Scholar Award from Hope College Biology Department