Investigating the Cytotoxic Effects of Mycobacteriophage Vix Gene 80
Dr. Joseph Stukey, Hope College
Dr. Virginia McDonough, Hope College
A bacteriophage, or phage, is a type of virus that infects and replicates in bacteria. To reproduce, the infecting 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. In work not published, I confirmed that the Vix80 gene product is also cytotoxic when expressed in Mycobacterium smegmatis. My hypothesis is that a physical interaction between the Vix80 gene product and a specific host cell protein affects cell metabolism and causes growth inhibition. My summer research goal was to test that hypothesis and work toward identifying the targeted host cell protein. Using molecular biological techniques, I tagged the N-terminus of the Vix80 protein with six histidine residues. The modified protein was then expressed in Escherichia coli and purified by column chromatography. SDS-PAGE and staining verified that I had expressed and purified the Vix80 protein of correct size. With the modified Vix80 protein confidently isolated, the next steps in my work will be to use the His-tagged Vix80 protein in a biochemical approach to identify the interacting host cell protein.
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