With this CAREER Award, the Organic and Macromolecular Chemistry program and the Cellular Systems Cluster program are supporting the research of Professor Herman O. Sintim of the University of Maryland, College Park. Professor Sintim will develop new chemical tools to study 3'-5'-cyclic diguanylic acid (c-di-GMP) signaling in bacteria. C-di-GMP, a common chemical messenger present uniquely in bacteria, plays a central role in bacterial biofilm formation and regulation of virulence-related factors in diverse bacteria. Several questions remain unanswered in c-di-GMP signaling in bacteria. For example, the environmental cues that modulate c-di-GMP signaling in bacteria and the identities of the adaptor proteins that respond to fluctuations in intracellular concentration of c-di-GMP remain largely uncharacterized. The first objective is to develop a fluorescent sensor for c-di-GMP. Such a sensor will be useful for establishing a link between different environmental cues and the intracellular concentrations of c-di-GMP. Secondly, a new solid-phase methodology will be used to prepare photo-affinity c-di-GMP analogs for the identification of c-di-GMP adaptor proteins. The identification of c-di-GMP binding proteins should help unravel the complex signaling network that c-di-GMP apparently regulates.
Professor Sintim will also establish four Percy Julian undergraduate research fellowships at the University of Maryland. This research fellowship will be open to underrepresented minorities in the sciences. Percy Julian fellows will be supported to conduct research in the laboratory of an established investigator at the University of Maryland. This fellowship provides the opportunity to nurture minority students at an early stage of their careers and encourage such students to consider a career in the sciences.
Bacterial infections affect millions of people every year, resulting in several deaths. The majority of bacteria that infect humans are biofilm-forming bacteria and it is believed that bacteria in a biofilm are more difficult to kill than free-living (or planktonic) bacteria. Consequently drugs that could inhibit bacterial biofilm formation have the potential to potentiate the effects of traditional antibiotics. Despite the critical role that bacterial biofilms play in antibiotic resistance, there is a paucity of medicines that can be used inhibit bacterial biofilm formation. This is probably because the mechanisms that lead to bacterial biofilm formation are not fully understood and the protein or nucleic acid macromolecules that are involved in bacterial biofilm formation have not been fully characterized. C-di-GMP has emerged as an important signaling molecule in a variety of bacteria, which regulates the biofilm phenotype. Therefore chemical tools that could be used to study c-di-GMP signaling in bacteria would be beneficial to the biofilm community. The intellectual merits of this grant were many. During the tenure of this NSF grant, we developed a simple synthesis of c-di-GMP and this facilitated the development of various c-di-GMP analogs that were then used to study the structure-activity-relationship (SAR) of c-di-GMP to various proteins and RNA riboswitches that regulate c-di-GMP signaling in bacteria. Insights gained from these SAR studies could be used in the future to design inhibitors of c-di-GMP signaling, which are predicted to be biofilm-modulating molecules. During the grant period, we also developed several assays (both fluorescence and colorimetric) to detect c-di-GMP in crude cell lysates. These assays are important tools that can be used to study how environmental conditions affect c-di-GMP concentration inside bacterial cells and because the concentration of c-di-GMP correlates with biofilm formation, our new c-di-GMP detection tools are being used to gain a deeper understanding of how nucleotides regulate bacterial physiology to affect the biofilm phenotype. This NSF grant also had numerous broader impacts. The grant was used to support many undergraduate researchers (called Percy Julian fellows) and many of the Percy Julian fellows have now proceeded to do advanced PhD or MD/PhD degrees at well respected programs and are expected to contribute to the US scientific and medical workforce in the future. Graduate students and postdoctoral researchers who were also supported by this NSF grant have gained employment as researchers or principal investigators at both academic and non-academic institutions.
