Investigating the Interaction between UDP-glucose: Glycoprotein glucosyltransferase (UGGT), a Key Gatekeeper of Glycoprotein Folding, and the 15 kDa selenoprotein (Sep15)

Presenter

Owen A. Hurlbut Lesk

Campus

UMass Amherst

Sponsor

Lila M. Gierasch, Department of Biochemistry and Molecular Biology, UMass Amherst

Schedule

Session 4, 2:30 PM - 3:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board C38, Poster Showcase Room (163), Row 4 (C31-C40) [Poster Location Map]

Abstract

One third of human proteins traverse the endoplasmic reticulum (ER), and this cellular compartment is critical for their maturation. It is in the ER that these proteins must adopt their native folded states, which are essential for their functional capacities. Protein folding within the ER is regulated by the key gatekeeper UDP-glucose: glycoprotein glucosyltransferase (UGGT), an enzyme which selectively moderates protein escape from the ER by only allowing proteins that have folded to their native states to continue to mature. However, the mechanism enabling UGGT to serve this critical role is yet unknown. Furthermore, UGGT associates with the 15 kDa selenoprotein (Sep15), and the impact of this interaction on UGGT substrate specificity or function are also unknown. Given limited structural information available for UGGT and Sep15, AlphaFold2 was utilized to predict the structures of both proteins and of the heterodimeric UGGT/Sep15 complex. By investigating the predicted UGGT/Sep15 interaction, we identified residues F243 and L262 of UGGT as likely critical for the assembly of this complex. Consequently, each of these residues was independently mutated to lysine, and co-immunoprecipitation of UGGT, wild type or mutant, with Sep15 used to assay the effect of each mutation on the formation of the UGGT/Sep15 complex. These results validated our predictions and elucidated critical residues on the UGGT/Sep15 interface and served as a starting point for investigations into UGGT. 

Keywords

structural biology, protein-protein interactions, AlphaFold, computational biology, secretory pathway

Research Area

Biological Organisms

SIMILAR ABSTRACTS (BY KEYWORD)