Nanodiscs to study membrane proteins

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Membrane proteins constitute nearly 30% of the cell content for all living organisms. Despite their great importance to life systems, scientists still struggle to study these macromolecules in a functionally active form that is compatible with experimentation. The manipulation of membrane proteins in vitro traditionally requires researchers to use methods such as lipid vesicles or detergent micelles that mimic the properties of the original biological membrane. However, these environments often reduce the activity of proteins, or in worse cases, produce results that are problematic to analyze due to membrane heterogeneity and protein aggregation. To help to circumvent the difficulties, a technology known as Nanodiscs, or Nanolipoparticles, is being developed to incorporate proteins into small (a few nanometer large) discoidal patches of membrane. This technology is novel and enable researchers to apply a variety of new experimental techniques because these particles are stable, homogeneous and water-soluble. The technology allowed my laboratory to understand the fundamental process of protein translocation across the bacterial membrane. In our proposed research program, we will further exploit the Nanodiscs in three different applications that will serve (i) to understand how specialized membrane transporters allow nutrients such as sugars to cross the bacterial membrane, (ii) to identify the molecular contacts that proteins need to establish with lipids in order to extract and transport cholesterol, and (iii) to discover the network of protein interactions taking place in the bacterial cell envelope using the latest tools of proteomics adapted to Nanodiscs. Each of these goals will contribute important new information to key cellular process that occurs at the membrane interface. Our research using the nanoscale lipid bilayers has strong potential for downstream biotechnological applications. It will also train my students and post-doctoral researchers with a wide range of skills, thereby preparing them for professional careers in either academic or industrial settings.