Prof. Philip R. Hardwidge
Prof. Philip R. Hardwidge
College of Veterinary Medicine, Kansas State University, USA
Title: YM155 Inhibits NleB and SseK Arginine Glycosyltransferase Activity
The type III secretion system effector proteins NleB and SseK are glycosyltransferases that glycosylate protein substrates on arginine residues. We conducted high‐throughput screening as‐says on 42,498 compounds to identify NleB/SseK inhibitors. Such small molecules may be useful as mechanistic probes and may have utility in the eventual development of anti‐virulence therapies against enteric bacterial pathogens. We observed that YM155 (sepantronium bromide) inhibits the activity of Escherichia coli NleB1, Citrobacter rodentium NleB, and both Salmonella enterica SseK1 and SseK2. YM155 was not toxic to mammalian cells, nor did it show cross‐reactivity with the mamma‐lian O‐linked N‐acetylglucosaminyltransferase (OGT). YM155 reduced Salmonella survival in mouse macrophage‐like cells but had no direct impact on bacterial growth rates, suggesting YM155 may have utility as a potential anti‐virulence inhibitor.
My research team is interested in understanding, treating, and preventing diarrheal disease caused by bacterial pathogens. We study several types of Escherichia coli that cause diarrhea and malnutrition in humans and livestock, including E. coli O157:H7 and enterotoxigenic E. coli (ETEC). These pathogens, as well as other enteric bacteria that use contact-dependent secretion systems, represent important threats to food safety, biosecurity, and animal health. In many cases, vaccines are not available or are ineffective, and the basic molecular microbiology of the host-pathogen interaction is poorly understood. We have discovered and characterized several mechanisms by which bacterial proteins subvert the host innate immune system and cytoskeletal dynamics to promote bacterial colonization and transmission. Recently we have described a previously unknown function of type III secretion system effectors in regulating bacterial physiology. We are currently directing our knowledge of these proteins and their mammalian targets to treating autoimmune disorders by engineering bacterial proteins to function as anti-inflammatory drugs. We are using CRISPR technologies to understand essential host determinants for several poorly-characterized bacterial and viral pathogens. We collaborate with industry to explore the utility of several ETEC vaccine candidates we have characterized. We are active in international collaborations with scientists in Australia, China, Denmark, England, Germany, South Korea, Spain, and Vietnam.