Major
Chemistry
Research Abstract
The phospholipid bilayer present in both eukaryotes and prokaryotes regulates the cell’s acquisition of nutrients and excretion of waste. Studies on the complex components of the lipid bilayer have paved the way for learning about the selective permeability of the membrane. It is of great interest to understand how materials are being transported through transmembrane proteins in relation to the electrochemical gradient. Investigation into the mechanistic properties of these transport proteins, particularly ATP-binding cassettes (ABC) transporters, can clarify how substrates are being transported via the binding and hydrolysis of adenosine triphosphate (ATP). The study of ABC transporters is significant in human disease treatment; for example, the alteration of the ATP transport protein domain has been found to lead to multidrug-resistance (Boumendjel, A., 2009) and cystic fibrosis (Mendoza, J., 2007). The overall goal of this project is to compare the activity of the MetNI transporter, a methionine importer, solubilized in detergent to the activity in nanodiscs, a self-contained lipidic environment (Sligar, 2008). First, the membrane-scaffolding protein (MSP) component of nanodiscs MSP3 was successfully bacterially expressed in E. coli cells on a large-scale and then purified by fast protein liquid chromatography (FPLC). Preliminary ATPase assays were conducted on detergent-solubilized MetNI. We calculated that the MetNI transporter isolated in detergent has an average Km of 619 µM and kcat of 4.3 min-1. The comparison of the MetNI ATPase rate in lipidic versus detergent environments will be carried out once MetNI is successfully reconstituted into nanodiscs.
Faculty Mentor/Advisor
Dr. Janet Yang
Included in
Examining the Bacterial Methionine Transporter Utilizing Soluble Lipid Bilayer Systems
The phospholipid bilayer present in both eukaryotes and prokaryotes regulates the cell’s acquisition of nutrients and excretion of waste. Studies on the complex components of the lipid bilayer have paved the way for learning about the selective permeability of the membrane. It is of great interest to understand how materials are being transported through transmembrane proteins in relation to the electrochemical gradient. Investigation into the mechanistic properties of these transport proteins, particularly ATP-binding cassettes (ABC) transporters, can clarify how substrates are being transported via the binding and hydrolysis of adenosine triphosphate (ATP). The study of ABC transporters is significant in human disease treatment; for example, the alteration of the ATP transport protein domain has been found to lead to multidrug-resistance (Boumendjel, A., 2009) and cystic fibrosis (Mendoza, J., 2007). The overall goal of this project is to compare the activity of the MetNI transporter, a methionine importer, solubilized in detergent to the activity in nanodiscs, a self-contained lipidic environment (Sligar, 2008). First, the membrane-scaffolding protein (MSP) component of nanodiscs MSP3 was successfully bacterially expressed in E. coli cells on a large-scale and then purified by fast protein liquid chromatography (FPLC). Preliminary ATPase assays were conducted on detergent-solubilized MetNI. We calculated that the MetNI transporter isolated in detergent has an average Km of 619 µM and kcat of 4.3 min-1. The comparison of the MetNI ATPase rate in lipidic versus detergent environments will be carried out once MetNI is successfully reconstituted into nanodiscs.
