Glutamate Carboxypeptidase II Transmembrane Computation Modelling Project

Indianapolis, IN

Glutamate Carboxypeptidase II (GCPII) is a transmembrane protein found in different human tissues, such as the small intestine, kidney and especially in the prostatic and nervous tissues. For example, GCP II protein is thought to be involved stroke progression by excessively hydrolyzing the neurotransmitter, N-Acetyl-L-Aspartyl-L-Glutamate (NAAG), whereas GCPII acts as a folate hydrolase in the intestine to help folic acid metabolism. However, GCPII in other tissues remain unknown, requiring thorough molecular level study in a setting that mimics the tissue-specific conditions. This work focuses on the interactions between GCPII and its surrounding membrane lipids. Four out of five GCPII paralogs contain a transmembrane region that vary in lipid composition. To fully understand the GCPII-membrane lipid interactions we are conducting in silico molecular modeling experiments as well as in vitro lipid nanodisc based studies. For in silico studies, the Modeller program was used to generate transmembrane helix regions of GCPII as no full-length GCPII structure is available. Using CHARMM-GUI program, we incorporated different lipids to mimic the tissue-specific lipid conditions. Additionally, VMD/ NAMD molecular dynamics programs were used for the analysis of our data. Varying lipid composition and synthetic peptides were used to generate lipid-nanodisc inserted transmembrane regions of GCPII and fluorescence spectroscopy is used to study the computer model predicted lipid-protein interactions. We perfected the synthesis of lipid nanodiscs in our lab for this study. We believe our lipid-protein interaction study will shed light on the tissue-specific functions of GCPII to help understand its role in physiology and disease development.