Using Chemistry to Probe Anthrax Toxin Protein Translocation

The mechanism of protein translocation across a cell membrane will be investigated. Nature has evolved a number of large proteins whose function is to enter mammalian cells. Some of these proteins are produced by bacteria and are often toxic to the host. An example of such a protein is anthrax toxin. The aim of the research is to use chemistry to uncover the molecular basis of anthrax toxin protein entry into cells. A battery of translocation assays and a protein modification toolkit, that allows at-will modification, will be used to investigate how the non-toxic forms of anthrax toxin enter cells. By virtue of taking a chemical approach, variants that contain chemical modifications at defined positions within these large anthrax protein complexes will be prepared and investigated in order to provide a fundamental understanding of the operation of these nanomachines. Research training at the graduate and undergraduate levels will expose students to the latest chemical methods that are used in these studies and provide them with insight into complicated biological processes. Additional effort will be put into an outreach chemical show. The PI together with MIT undergraduate students will perform chemical demonstrations that appear to be magical to an audience of 8-12 year old students. The teaching philosophy is that magic will capture the youths' attention and excite them about science. The long-term aim of outreach program is to springboard young patrons into careers of fundamental science.

This research project will systematically uncover the role of cargo on translocation across a membrane and design charged peptides for heterologous protein passage through a protective antigen pore. The research procedures will employ a protein modification toolkit that allows at-will modification and investigation of the anthrax toxin nanomachine. The studies proposed here will provide a mechanistic understanding of protein translocation across a membrane and lay the foundation for using semi-synthetic strategies to probe the translocation process. In addition, the tools and insights gleaned from these studies will allow the development of inhibitors and methods to deliver novel chemical forms into cells, which is a longstanding problem in chemistry.