CAREER: Structure-function studies of bacterial toxin-ribosome complexes

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ABSTRACTProkaryotes have evolved effective and efficient ways to rapidly respond to and survive diverse environmental stresses through global regulatory responses. This is achieved by adjusting rates of intracellular metabolic processes that halt essential growth processes such as DNA replication, RNA transcription and protein synthesis. Toxin-antitoxin (TA) modules facilitate cell survival during such times. In addition, TA systems have also been implicated in biofilm formation, bacterial persistence during antibiotic treatment and bacterial pathogenesis. These diverse functions underpin the importance of determining how recognition of cellular targets is achieved to facilitate cell survival. During times of nutritional stress, bacteria turn to TA systems to fine tune basic cellular processes. In distinct contrast to classic bacterial toxins such as anthrax, cholera or diptheria, the toxin component of a TA system is normally present in cells bound to an antitoxin that specifically blocks its activity. Under stress conditions, the antitoxin is degraded and the toxin released to exert its effect, most commonly ribonuclease activity against messenger RNA. The research in the Dunham laboratory focuses on a novel toxin protein that codon-specifically degrades mRNA, but only when bound to a translating ribosome. This research entails the use of an integrated structural biology and biochemical approach to answer key questions of RNA-protein recognition and catalysis and to provide a deeper understanding of the toxin mediated mRNA degradation.Broader Impacts: The Broader Impacts of this research include the involvement of students in all aspects of this project from learning to purify ribosomes, overexpression and purification of recombinant proteins, in vitro transcription of RNA and in vitro translation assays. In addition, students will gain experience at the forefront of structural biology, learning about techniques that are required to solve large macromolecular complexes. The PI will sponsor two summer undergraduate students through the Emory summer undergraduate program and from an all women?s college to encourage the pursuit of a scientific career. Lastly high school students and teachers will get hands-on experience in a joint Emory-Georgia Tech summer program designed to study extremophile ribosomes.