Collaborative Research: Chemical Tools to Elucidate Glycolipid Biosynthesis and Transport in the Corynebacterineae

With the support of the Chemistry of Life Processes (CLP) program in the Division of Chemistry, Professors Benjamin Swarts of Central Michigan University and Mary Jackson of Colorado State University are developing chemical tools to investigate a class of complex glycolipids, or sugar-linked lipid molecules, that are present in the cell envelope of hundreds of bacterial species from the suborder Corynebacterineae. These glycolipids, which are referred to as phosphatidylinositol mannosides (PIMs), play essential roles in bacterial cellular defense, integrity, and immunological activity. While PIMs and related molecules are unique to the Corynebacterineae and contribute to these organisms’ distinctive physiological and pathogenic characteristics, many aspects of how these glycolipids are constructed and organized in bacterial cells remain unknown. Such knowledge gaps remain because PIMs are challenging to study using traditional techniques and there is a lack of modern tools for analyzing them. This project seeks to develop new chemical biology tools to allow specific tagging and tracking of PIMs and related glycolipids in cellular contexts. Applications of this toolbox could provide a better understanding of how the Corynebacterineae construct their cell envelope. Undergraduate and graduate students and a postdoctoral fellow working on this research will acquire interdisciplinary training in organic synthesis, chemical biology, and microbiology. To promote interdisciplinary training and communication, students and postdocs at both institutions will meet regularly virtually to discuss the project. This project will be integrated into an outreach program to introduce community college students to chemical bacteriology research and to encourage their continued education in STEM (science, technology, engineering and mathematics). The tools generated in this project are expected to be broadly applicable and support other scientists pursuing research on the Corynebacterineae.Phosphatidylinositol mannosides (PIMs) and their highly glycosylated derivatives, lipomannan (LM) and lipoarabinomannan (LAM), are difficult to investigate using traditional techniques of biochemistry and molecular biology because they consist of highly complex, non-genetically encoded lipids and sugars. To address this problem, this research project seeks to develop synthetic carbohydrate-based probes that exploit native and genetically engineered metabolic pathways to introduce chemical tags into PIMs, LM, and LAM in live bacteria. Fluorescently labeled glycolipid molecules will be tested in whole cells, potentially providing a means to track the glycolipids specifically in a cellular context. The probes developed in this project are expected to provide information on (i) the spatiotemporal dynamics of PIM, LM, and LAM construction in live bacterial cells; and (ii) the identity of the protein(s) that is/are responsible for transport of PIMs across the bacterial inner membrane. The findings from this project are expected to provide an improved understanding of glycolipid biosynthesis and dynamics, which could provide insight into the physiology of bacteria in the Corynebacterineae suborder.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.