Mechanisms of macrolide synergy in Mycobacterium tuberculosis

摘要

ABSTRACT I have been fortunate to combine my passions for scientific research and public health in my doctoral studies at the Harvard T. H. Chan School of Public Health. My goal is to combine creativity and technical skills in drug discovery efforts against infectious diseases of high morbidity and mortality. Dr. Eric Rubin's lab is the archetype for rigorous scientific training and creative problem-solving. He and I have established my core training goals. I hope not only to complete my proposed research plan, but also to continue sharpening skills in grant and paper writing, collaboration, critical thinking, and quantitative data analysis. An F31 Fellowship will propel me in my journey to become a principal investigator in the field of antibiotic research and discovery. Mycobacterium tuberculosis (Mtb), which causes tuberculosis (TB), has been a leading cause of infectious disease morbidity and mortality for thousands of years. One major reason for its global persistence is the fact that Mtb is intrinsically resistant to most antibiotics. Current treatment requires months of combination therapy with drugs almost exclusively reserved for TB and that are not well-tolerated by patients. The high morbidity, mortality, and the growing prevalence of acquired drug resistance in TB motivate an urgent search for new drugs. If bacterial targets could be identified that synergize with existing drugs, such as to bring efficacy to antibiotics not currently effective against TB, they could advance our goal of treatment improvement. I have used a genetic approach to identify an essential Mtb enzyme that, when depleted, sensitizes this pathogen to existing antibiotics. Here, I propose to characterize the mechanisms of synergy between this Mtb gene and macrolide antibiotics, which bind the 50S ribosomal subunit to inhibit translation. Macrolides are inexpensive and well- tolerated antibiotics used to treat other infectious diseases. My gene of interest, pth, encodes the essential enzyme peptidyl tRNA hydrolase, a translation rescue factor that cleaves tRNA from peptides when they are prematurely released from stalled ribosomes. My approach to studying Pth as an antibiotic target draws on existing analytical techniques, as well as a new method using tRNA-sequencing that I have developed for studying charged tRNA pools. Investigating synergistic drug targets and their mechanisms of interaction will allow us to lend new efficacy to old compounds in the fight against TB. Additionally, new tools to study tRNA will allow us to expand our understanding of translation machinery in other organisms.