PRMT5, Which Forms Distinct Homo-oligomers, Is a Member of the Protein-arginine Methyltransferase Family

Abstract

We found that JBP1, known as a human homolog (Skb1Hs) of Skb1 of fission yeast, interacts with NS3 of the hepatitis C virus in a yeast two-hybrid screen. Amino acid sequence analysis revealed that Skb1Hs/JBP1 contains conserved motifs of S-adenosyl-L-methionine-dependent protein-arginine methyltransferases (PRMTs). Here, we demonstrate that Skb1Hs/JBP1, named PRMT5, is a distinct member of the PRMT family. Recombinant PRMT5 protein purified from human cells methylated myelin basic protein, histone, and the amino terminus of fibrillarin fused to glutathione S-transferase. Myelin basic protein methylated by PRMT5 contained monomethylated and dimethylated arginine residues. Recombinant glutathione S-transferase-PRMT5 protein expressed in Escherichia coli also contained the catalytic activity. Sedimentation analysis of purified PRMT5 on a sucrose density gradient indicated that PRMT5 formed distinct homooligomeric complexes, including a dimer and tetramer, that comigrated with the enzyme activity. The PRMT5 homo-oligomers were dissociated into a monomer in the presence of a reducing agent, whereas a monomer, dimer, and multimer were detected in the absence or at low concentrations of a reducing agent. The results indicate that both covalent linkage by a disulfide bond and noncovalent association are involved in the formation of PRMT5 homo-oligomers. Western blot analysis of sedimentation fractions suggests that endogenous PRMT5 is present as a homo-oligomer in a 293T cell extract. PRMT5 appears to have lower specific enzyme activity than PRMT1. Although PRMT1 is known to be mainly located in the nucleus, human PRMT5 is predominantly localized in the cytoplasm.Protein arginine methylation is an irreversible, post-translational covalent modification. Protein-arginine methyltransferases (PRMTs) 1 transfer the methyl group from S-adenosyl-L-methionine to the guanidino nitrogen atoms of an arginine residue (1). PRMTs are classified into two major types, I and II, based on substrate and reaction product specificity. Both type I and II PRMTs are common in the formation of monomethylarginine, but the two differ in that type I PRMT catalyzes asymmetric dimethylarginine, whereas type II PRMT produces symmetric dimethylarginine. Type I PRMTs methylate arginines in the Arg-Gly-Gly-rich region, known as the RGG motif, present in many RNA-binding proteins (2-4), or in the ArgXaa-Arg motif in poly(A)-binding protein II (5). Myelin basic protein (MBP) and the spliceosomal D1 and D3 proteins are the only known in vivo substrates for type II

Histone arginine methylation is required for vernalization-induced epigenetic silencing of FLC in winter-annual Arabidopsis thaliana

“…1C) (18). An alignment of the predicted primary amino acid sequence of At4g31120 to protein databases revealed high sequence identity to human PRMT5 (Protein Arginine Methyltransferase 5) (19). An additional At4g31120 mutant was isolated from the Salk T-DNA collection (Fig.…”

Protein Arginine Methyltransferase Prmt5-Mep50 Methylates Histones H2A and H4 and the Histone Chaperone Nucleoplasmin in Xenopus laevis Eggs

“…The stoichiometry of the Prmt5-Mep50 complex is currently unknown, although previous reports show oligomer formation for Prmt5 (53). Endogenous and recombinant Prmt5-Mep50 complexes elute from sizing columns at high apparent molecular weight (Fig.…”

Arginine methylation regulates mitochondrial gene expression in Trypanosoma brucei through multiple effector proteins

“…3), indicating that this residue is methylated by another enzyme. We have identified a homolog of the type II protein arginine methyltransferase, PRMT5 (Branscombe et al 2001;Rho et al 2001), in the T. brucei genome. This protein, which we term TbPRMT5, possesses methyltransferase activity and is a likely candidate for catalyzing RBP16 R93 methylation (D. Pasternack and L. Read, unpubl.).…”