Assessment of thiol oxidation of a protein arginine methyltransferase
Class
Article
Department
Chemistry and Biochemistry
Faculty Mentor
Joan Hevel
Presentation Type
Poster Presentation
Abstract
PRMT1 is one of nine enzymes in the human protein arginine methyltransferase (PRMT) family. These enzymes catalyze the transfer of the methyl group from the methyl donor S-adenosylmethionine (AdoMet) to arginine residues of target protein and peptide substrates, producing either a monomethylated or dimethylated product. This modification can alter the structure and activity of the targeted proteins. Arginine methylation is involved in a wide range of cellular processes. Its dysfunction has been implicated in a number of pathological conditions, including cancer and heart disease. Accordingly, regulation of the PRMT enzymes has emerged as a topic of interest. We have demonstrated that PRMT1 activity is markedly lower in oxidized samples compared to reduced samples. Additionally, we have performed kinetic assays on several PRMT1 cysteine-to-serine variants which indicate that multiple cysteine residues are involved in this response. Cysteine contains a thiol group which can be oxidized to form sulfenic acid, sulfonic acid or, in the presence of another thiol group, disulfide bonds. The presence of any of these sulfur moieties in PRMT1 could alter the activity of the enzyme. We have optimized an assay based on a fluorescently labeled iodoacetamide which forms a covalent bond with fully reduced sulfhydryl groups. This allows us to compare the relative level of oxidation between samples. Here we present evidence that oxidized PRMT1 shows a lower ratio of cysteine sulfhydryl groups when compared to reduced samples. This research helps to establish a link between cysteine oxidation and a reduction in PRMT1 activity. It also helps to form a base for further research into determining the mechanism and regulatory role of PRMT1 inhibition by oxidation.
Start Date
4-9-2015 3:00 PM
Assessment of thiol oxidation of a protein arginine methyltransferase
PRMT1 is one of nine enzymes in the human protein arginine methyltransferase (PRMT) family. These enzymes catalyze the transfer of the methyl group from the methyl donor S-adenosylmethionine (AdoMet) to arginine residues of target protein and peptide substrates, producing either a monomethylated or dimethylated product. This modification can alter the structure and activity of the targeted proteins. Arginine methylation is involved in a wide range of cellular processes. Its dysfunction has been implicated in a number of pathological conditions, including cancer and heart disease. Accordingly, regulation of the PRMT enzymes has emerged as a topic of interest. We have demonstrated that PRMT1 activity is markedly lower in oxidized samples compared to reduced samples. Additionally, we have performed kinetic assays on several PRMT1 cysteine-to-serine variants which indicate that multiple cysteine residues are involved in this response. Cysteine contains a thiol group which can be oxidized to form sulfenic acid, sulfonic acid or, in the presence of another thiol group, disulfide bonds. The presence of any of these sulfur moieties in PRMT1 could alter the activity of the enzyme. We have optimized an assay based on a fluorescently labeled iodoacetamide which forms a covalent bond with fully reduced sulfhydryl groups. This allows us to compare the relative level of oxidation between samples. Here we present evidence that oxidized PRMT1 shows a lower ratio of cysteine sulfhydryl groups when compared to reduced samples. This research helps to establish a link between cysteine oxidation and a reduction in PRMT1 activity. It also helps to form a base for further research into determining the mechanism and regulatory role of PRMT1 inhibition by oxidation.