Developing a Physical Model of O-GlcNAc Transferase (OGT) in Complex with TAB1

O-GlcNAcylation is a post-translational modification similar in importance to the mechanism of phosphorylation in its ability to affect signal transduction. This process is mediated by the enzyme, O-GlcNAc transferase (OGT). OGT catalyzes the addition of the sugar, N-acetylglucosamine (GlcNAc) from the carrier molecule Uridine Diphosphate N-acetylglucosamine (UDP-GlcNAc), to certain serine or threonine residues in target substrate proteins. The mechanisms by which OGT recognizes its protein substrates, and the details of the molecular interactions between the substrate and enzyme, are still poorly understood. The CREST (Connecting Researchers, Educators, and STudents) team at Nova Southeastern University (NSU) created a physical model of the OGT protein in complex with the fused substrate peptide from TAB1 (a transforming growth factor-beta-activated kinase 1 binding protein involved in a variety of signaling cascades including pro-inflammatory pathways). Details of this protein and its fusion with a segment of the substrate peptide from TAB1 were found in the Protein Data Bank file, 5LVV, and imported into Jmol, a protein visualization software. Specific program commands were utilized in Jmol to manipulate the original file into a format that was later able to be 3-D printed to create an instructional molecular model. Various features of the OGT fused with the TAB1 substrate peptide were highlighted. Such highlighted features include the regions upstream and downstream of the of the substrate binding sequence. The region upstream is a His6-tag, while the region downstream is a 3xGly linker segment. Additionally, the fused substrate peptide from TAB1 was highlighted as well as the specific serine that functions as the O-GlcNAc binding site on the TAB1 substrate. The N and C termini of the OGT were colored blue and red respectively. The overall focus of this project was to explore protein structure and design and build a physical model that illustrates key functional features of the protein. It was funded in part by NSF-DUE 1725940 for the CREST (Connecting Researchers, Educators, and STudents) Project. Developing 3-D molecular models in this way is a relatively inexpensive process to visually represent important biological relationships that can be useful for students, professors, and others trying to understand and explain complex molecular pathways