Investigating the Substrate Specificity of PRMT1 using a Plate-Based Screening Method

Research Authorship:

Tina Sawatzky, Sarah Mann and Dr. Bryan Knuckley

Faculty Mentor:

Dr. Bryan Knuckley | College of Arts and Sciences | Department of Chemistry

Abstract:

Enzymes are biological catalysts that speed up the rate of a reaction by lowering the activation energy and converting substrate (reactant) to product more expeditiously. Enzymes have a high degree of specificity and will only catalyze selective reactions by targeting particular substrates. In mammals, there exists a family of 11 enzymes, PRMT’s (Protein Arginine Methyl transferase), that target protein arginine for post translational methylation on the guanidino nitrogen of the residue. They occur naturally as Type I, II and III and can administer asymmetric di-methylation (ADMA), symmetric dimethylation (SDMA) and monomethylation, respectively. The focal point of this project is to determine the substrate specificity of PRMT1 (Type I), PRMT 4, (Type I) and PRMT5 (Type II) on arginine residues in histone tails. Histones are eukaryotic proteins. The “tails” of the histones (polypeptide chains) are projected out from the protein and are often targets of various post translational modifications (PTM’s). Overexpression of PRMT 1 and PRMT 4 results in increased enzyme activity leading to ADMA on the histones arginine’s. This modification recruit’s transcription factors to the histone tails and induces the transcription of cancerous genes (colon, breast, prostate cancer, etc.). Meanwhile, PRMT 5 is repressive of these developments by leading to SDMA on the arginine, which blocks the enzyme activity and recruitment of these same transcription factors.  By synthesizing the histone H4 tail in this experiment and varying different regions using high-throughput libraries, a screening of PRMT1, 4 and 5 can be completed.