Medical Health Broad Portfolio Research Career Scientist Award Application

Salmonella enterica causes a spectrum of clinical diseases that range from typhoid fever to non-typhoidal salmonellosis. Typhoid fever, a syndrome caused by the human- adapted serovars Typhi and Paratyphi, claims about 600,000 lives annually. Non- typhoidal Salmonella serovars like Typhimurium contribute to 1.4 million cases of diarrhea in the US alone and are responsible for roughly 200,000 deaths worldwide yearly. Multidrug resistance Salmonella clinical isolates more than doubled from 2011 to 2013. The World Health Organization has ranked Salmonella among the top 12 antibiotic resistant bacterial threats to global health. Salmonellosis afflicts active military servicemen and women deployed abroad, and non-typhoidal Salmonella infections are common among inpatients at VA hospitals. Among veterans and their families, the very young and the very old are disproportionally affected by non-typhoidal Salmonella. Non-typhoidal Salmonella infections cause life-threatening disseminated disease in immunocompromised people with HIV or cancer comorbidities, which are prevalent among the VA population. The goal of this Research Career Scientist Award is to apply our knowledge of Salmonella virulence to the development of novel antibiotics against multidrug resistant bacterial pathogens. The resistance of pathogenic bacteria to antibiotics is greatly regulated by the transcription factor DksA. The DksA protein binds to the secondary channel of RNA polymerase, regulating the kinetics of transcription of translational machinery, central metabolism and virulence gene programs. We will continue to search the molecular mechanisms by which DksA regulates Salmonella transcriptional programs and explore the therapeutic potential of antibiotics that bind to an evolutionarily conserved pocket in the coiled-coil domain of DksA. The Research Career Scientist Award will allow us to continue with our goal of developing patentable new chemical entities with antibiotic activity. Binding of DksA to RNA polymerase is in competition with Gre factors. While DksA regulates initiation of transcription, Gre factors control elongation and the fidelity of transcription. We have found that Gre proteins are essential for Salmonella virulence and the resistance of this Gram-negative rod to antibiotics. We plan to characterize the role Gre factors play in resolving transcriptional pauses at uridine-rich stretches in the 5'- untranslated regions of horizontally acquired virulence genes, thereby promoting bacterial pathogenesis and antibiotic resistance. The research in my laboratory involves multiple scientific collaborators at the Rocky Mountain VA Medical Center, the Atlanta VA Medical Center, the Wisconsin-Madison VA Medical Center and the Ann Arbor VA Healthcare System. We also collaborate with many investigators nonaffiliated with VA centers. As an integral component of this Research Career Scientist Award, I will continue training junior faculty, graduate students and postdoctoral fellows. In collaboration with other investigators at VA Medical Centers, I will mentor talented CDA candidates in their quest to become independent investigators, as I have had the privilege to do in the past, and thereby train the next generation of outstanding VA scientists.