Naomi Ward, 1656637, Why do bacteria need sterols?
Part I Non-technical: This project pursues a fundamental question in cell biology: why do bacteria make sterols? Sterols are lipid (fat) molecules that have multiple biological roles in eukaryotic (human, animal, and plant) cells. These roles include maintaining the structure and function of cell membranes. The best-known sterol is probably cholesterol. Sterols are also produced by some bacteria, but their purpose is unknown because bacterial cell membranes are not reported to need sterols. Discovering the purpose of bacterial sterols will make a significant contribution because knowledge of sterol function, in general, will be expanded. This is of broader relevance to society because of the fundamental importance of sterols as cellular building blocks, but also in more practical terms. For example, sterols such as cholesterol are essential in human physiology, and fungal sterol synthesis can be targeted by specific drugs to treat fungal infections. The project will also enhance the country's scientific workforce by providing cutting edge training in modern biological and analytical chemistry technologies.
Part II Technical: The project goal is to determine the role of sterols in Gemmata obscuriglobus, the first bacterium in which sterols have been shown to be essential. G. obscuriglobus possesses a unique constellation of eukaryote-like, sterol-associated, cellular features, including budding replication, complex intracellular membranes, and endocytosis-like behavior. The central hypothesis is that that Gemmata sterols have an expanded functional repertoire relative to eukaryotic sterols, including known functions of sterols in eukaryotes, as well as novel functions specific to a bacterial cellular context. The rationale for the proposed research is that it will expand our functional and evolutionary understanding of sterols, and uncover overlaps in the roles of eukaryotic and prokaryotic sterols. The project objective will be achieved by pursuing the following Specific Aims: (1) Determine how G. obscuriglobus sterols support budding replication; (2) Identify the contribution of G. obscuriglobus sterols to endocytosis-like activity; (3) Establish the effect of sterols on phospholipid metabolism in G. obscuriglobus. Research methods include microscopy, proteomics, and lipidomics. The expected outcome of the project is an improved understanding of sterol function, and the potential contribution of sterols to bacterial membrane-mediated processes characteristic of eukaryotes, as well as novel functions specific to bacteria. This will have important positive impact because it will potentially reveal previously undetected similarities and differences in prokaryotic and eukaryotic cell structures and functions. Broader Impacts include the Microbestiary, a unique science-art education and outreach project, where microbes and their cell structures serve as the subject matter. Multiple education and outreach products, including K-12 participation, will be generated, and the Microbestiary will be incorporated into undergraduate teaching in the humanities and sciences. Participation in this project will provide interdisciplinary training in cell biology and analytical chemistry for graduate and undergraduate students, who will also be key personnel for creating and disseminating the Microbestiary.
