A Proteomic Analysis of Arginine-methylated Protein Complexes

Abstract

Arginine methylation is a post-translational modification that results in the formation of asymmetrical and symmetrical dimethylated arginines (a-and sDMA). This modification is catalyzed by type I and II protein-arginine methyltransferases (PRMT), respectively. The two major enzymes PRMT1 (type I) and PRMT5 (type II) preferentially methylate arginines located in RG-rich clusters. Arginine methylation is a common modification, but the reagents for detecting this modification have been lacking. Thus, fewer than 20 proteins have been identified in the last 40 years as containing dimethylated arginines. We have generated previously four arginine methyl-specific antibodies; ASYM24 and ASYM25 are specific for aDMA, whereas SYM10 and SYM11 recognize sDMA. All of these antibodies were generated by using peptides with aDMA or sDMA in the context of different RG-rich sequences. HeLa cell extracts were used to purify the protein complexes recognized by each of the four antibodies, and the proteins were identified by microcapillary reverse-phase liquid chromatography coupled on line with electrospray ionization tandem mass spectrometry. The analysis of two tandem mass spectra for each methyl-specific antibody resulted in the identification of over 200 new proteins that are putatively arginine-methylated. The major protein complexes that were purified include components required for pre-mRNA splicing, polyadenylation, transcription, signal transduction, and cytoskeleton and DNA repair. These findings provide a basis for the identification of the role of arginine methylation in many cellular processes.

Molecular characterisation and inductive expression of a fish protein arginine methyltransferase 1 gene in response to virus infection

“…PRMT1 is the predominant and essential arginine methyltransferases in human cell, responsible for at least 85% of all arginine methylation reactions [24]. This result is consistent with the findings that most of the identified substrates are catalysed by PRMT1 [25,26], and that PRMT1 is vital for the early development of mice in that PRMT1 À/À mice die beyond embryonic days 6.5 [27]. PRMT1 is believed to preferentially catalyse proteins that interact with nucleic acids, such as histone H3 and H4, components of hnRNP, fabrillarin and nucleolin, to regulate protein-protein interactions [26].…”

“…So far the functional consequence of arginine methylation by PRMT is much less understood than those of the other post-translation modifications such as phosphorylation or acetylation. However, a recent proteomic study using four arginine methyl-specific antibodies has identified over 200 putative methylated proteins, which show that arginine methylation may be required for many cellular processes including signal transduction, the cytoskeleton, DNA repair, transcription, translation, and apoptosis [25]. In this study, flounder PoPRMT1 gene was cloned and the up-regulation by virus infection was verified in vitro and in vivo, indicating that PoPRMT1 might be implicated in fish antiviral immune response.…”

The PRMT1 gene expression pattern in colon cancer

“…Protein arginine methyltransferase 1 is a multifunctional protein, implicated in diverse biological processes, such as DNA repair, signal transduction, protein trafficking and RNA processing (McBride and Silver, 2001;Boisvert et al, 2003;Bedford and Richard, 2005;Lee et al, 2005b). Protein arginine methyltransferase 1 methylates a number of hnRNP molecules, playing a role in the shuttling of these proteins between the cytoplasm and the nucleus (Herrmann et al, 2004), and histone H4 at arginine 3 (Wang et al, 2001), a modification that functions as a transcription activation mark.…”

MN1-TEL, the product of the t(12;22) in human myeloid leukemia, immortalizes murine myeloid cells and causes myeloid malignancy in mice

“…Interestingly, this region contains an arginine-methyltransferase target sequence (amino acids 939-947). 43 Arginine methylation is important for transcriptional activation of nuclear receptor transcription complexes, 44 and given MN1's interaction with RARa-RXR dimers, 34 this methylation sequence might contribute to MN1's function, a possibility we are investigating.…”