Heterogeneous nuclear ribonucleoprotein E1B-AP5 is methylated in its Arg-Gly-Gly (RGG) box and interacts with human arginine methyltransferase HRMT1L1.
The heterogeneous nuclear ribonucleoprotein (hnRNP) family includes predominantly nuclear proteins acting at different stages of mRNA metabolism. A characteristic feature of hnRNPs is to undergo post-translational asymmetric arginine methylation catalysed by different type 1 protein arginine methyltransferases (PRMTs). A novel mammalian hnRNP, E1B-AP5, recently identified by its interaction with adenovirus early protein E1B-55 kDa, has been proposed to have a regulatory role in adenoviral and host-cell mRNA processing/nuclear export [Gabler, Schutt, Groitl, Wolf, Shenk and Dobner (1998) J. Virol. 72, 7960-7971]. Here we report that E1B-AP5 is methylated in vivo in its Arg-Gly-Gly (RGG)-box domain, known to mediate protein-RNA interactions. The activity responsible for E1B-AP5 methylation forms a complex with E1B-AP5 in vivo. The predominant mammalian arginine methyltransferase HRMT1L2 (hPRMT1) did not detectably methylate endogenous E1B-AP5 despite efficiently methylating a recombinant RGG-box domain of E1B-AP5. Using yeast two-hybrid screening we identified HRMT1L1 (PRMT2) as one of the proteins interacting with E1B-AP5. By in situ immunofluorescence we demonstrated that E1B-AP5 co-localizes with the nuclear fraction of HRMT1L1. The Src homology 3 (SH3) domain of HRMT1L1 was essential for its interaction with E1B-AP5 in vivo. We suggest that HRMT1L1 is responsible for specific E1B-AP5 methylation in vivo.
Kzhyshkowska
J
J
Institut für Medizinische Mikrobiologie und Hygiene, Universität Regensburg, D-93053 Regensburg, Germany. julia-k@gmx.net
Schütt
H
H
Liss
M
M
Kremmer
E
E
Stauber
R
R
Wolf
H
H
Dobner
T
T
D020816:Amino Acid Motifs; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D006367:HeLa Cells; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D011484:Protein-Arginine N-Methyltransferases; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D018909:src Homology Domains
D034441:Heterogeneous-Nuclear Ribonucleoproteins; D047908:Intracellular Signaling Peptides and Proteins; D012261:Ribonucleoproteins; D008780:Methyltransferases; C077013:PRMT2 protein, human; D011484:Protein-Arginine N-Methyltransferases