Studying the Impact of Lysine Modifications on the Activity of Protein Disulfide Isomerase

Recent studies have shown that protein activity can be regulated through lysine acetylation, and Dr. Mutus’ lab has been investigating the role of lysine residue modifications on the catalytic activity of Protein Disulfide Isomerase (PDI). PDI is a protein which contains five domains and is part of the Thioredoxin superfamily. The physiological role of PDI is to catalyze the oxidation, reduction, or isomerization of free thiols or disulfide bonds of proteins; these oxioreductase reactions allow redox-dependant chaperone activity to occur. The oxioreductase activity occurs through a CXXC motif, found on both the a and a’ domains. Previous research in Dr. Mutus’ lab has shown that two lysine residues, lysine 57 flanking the a domain active site, lysine 401 flanking the a’ domain active site, allow for optimal catalytic activity. Site directed mutagenesis of lysine residues 81, and 424, to glutamic acid, as well as chemical acetylation of lysine residues by treatment with acetic anhydride, will be used in order to study the effects of additional lysine residues on PDI’s activity. This research provides insight into potentially critical lysine residues which may regulate PDI’s oxioreductase activity through interactions with the CXXC motif. These residues are candidates for acetylation in vivo for further study on PDI’s regulation