Human Protein Arginine Methyltransferase 7 (PRMT7) Is a Type III Enzyme Forming ω-N-Monomethylated Arginine Residues

Abstract

Background: PRMT7 is a poorly characterized member of the family of protein arginine methyltransferases (PRMTs) that catalyze the modification of a wide group of proteins. Results: A bacterially expressed fusion protein of human PRMT7 produces only -monomethylated arginine (-MMA) derivatives. Conclusion: PRMT7 is a type III PRMT distinct from type I and type II PRMTs characterized to date. Significance: -MMA may be a distinct post-translational modification.

Mammalian Protein Arginine Methyltransferase 7 (PRMT7) Specifically Targets RXR Sites in Lysine- and Arginine-rich Regions

“…GST-GAR was expressed in E. coli BL21 Star (DE3) cells (Invitrogen, C601003) and purified with glutathione-Sepharose 4B beads (Amersham Biosciences) by affinity chromatography as described previously (5). Recombinant human histone H2A (GenBank TM accession number AAN59960), H2B (GenBank TM accession number AAN59961), H3.3 (GenBank TM accession number P84243), and H4 (GenBank TM accession number AAM83108) were purchased from New England Biolabs as 1 mg/ml solutions in 20 mM sodium phosphate, 300 mM NaCl, and 1 mM EDTA.…”

“…Chromatography-Amino acid analysis was performed to determine the products of enzymatic methylation reactions as described previously (5). Briefly, the hydrolyzed samples were mixed with 1 mol each of -MMA (acetate salt, Sigma, M7033), SDMA (di(p-hydroxyazobenzene)-pЈ-sulfonate salt, Sigma, D0390), and ADMA (hydrochloride salt, Sigma, D4268) as internal standards.…”

“…A sole type III activity forming MMA has been reported (4,5) as well as a type I/type II activity forming both ADMA and SDMA (16). A sole type III activity was also found for the worm and trypanosome homologs of PRMT7 (17,18).…”

“…PRMT5 catalyzes the formation of MMA and -N G , NЈ G -symmetric dimethylarginine (SDMA) and is defined as a type II PRMT. More recently, PRMT7 has emerged as a type III PRMT that produces only MMA in its substrates (4,5). In humans and mice, PRMT7 is a 692-amino acid protein with an ancestral duplication of the catalytic domains, both of which are required for its activity (4).…”

Crystal structure of the human PRMT5:MEP50 complex

“…Type I PRMT enzymes (PRMT1, -2, -3, -4, -6, and -8) generate ω-NG-monomethyl and ω-NG,NG-asymmetric di-methyl arginines, whereas PRMT5 is a type II PRMT that catalyzes the formation of ω-NG-monomethyl and ω-NG,N′G-symmetric di-methyl arginine residues. PRMT7 was initially thought to have type II activity, but recent evidence suggests that it may be a type III enzyme that is only able to monomethylate substrates to form ω-NG-monomethyl arginine (6). A type IV enzyme that catalyses the formation of δ-N-methyl arginine has been identified in yeast (7).…”