CAREER: Biosynthesis of lipid monolayer membranes in Bacteria

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Cell membranes define the physical boundary between life and the environment. This project will substantially increase our understanding of monolayer cell membranes, which are variations in membrane structure that may help microbes survive in stressful environments. Uncovering the biological role of monolayer membranes, and the biochemistry required to produce them, will reveal some of the mechanisms microbes use to inhabit diverse and in some cases harsh environments. Improved understanding of monolayer membranes will also open new avenues in engineering microbes for biotechnology. Local high school students and undergraduates will participate in the research. Collaborations between researchers, participating students, and high school teachers will result in a high school teaching module focused on environmental microbiology. An additional outcome of this project will be the creation of an interactive regional soil database.This project will define the environmental constraints and biochemical mechanisms that govern production of membrane-spanning lipids and monolayer cell membranes in the Acidobacteria. Functional roles for lipid monolayers and membrane-spanning lipids remain elusive. Membrane-spanning lipids are hypothesized to provide increased tolerance to elevated temperatures and low pH, as they are often associated with extremophilic lifestyles. However, their presence in numerous mesophilic prokaryotes, such as soil-dwelling bacterial species, has muddled this conclusion. This project will directly explore the connections between monolayer membranes, bacterial cell physiology, and biosynthesis of membrane-spanning lipids (branched dialkylglycerol tetraester and tetraether lipids) using tractable Acidobacteria model systems. One objective is to generate an environment to phenotype map for membrane-spanning lipid production. Another objective will be to identify and characterize biochemical processes involved in membrane-spanning lipid biosynthesis. Both objectives will utilize lipidomic, transcriptomic, and comparative genomic approaches to identify key regulatory and enzymatic pathways involved in producing branched dialkylglycerol tetraester and tetraether lipids. An additional component will be introducing membrane-spanning lipid biosynthetic capabilities to other bacterial species. Collectively, these objectives will deepen our understanding of the relationship between lipid structure, membrane function, and cell physiology in prokaryotes.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.