Protein arginine methyltransferase Prmt5-Mep50 methylates histones H2A and H4 and the histone chaperone nucleoplasmin in Xenopus laevis eggs.
Histone proteins carry information contained in post-translational modifications. Eukaryotic cells utilize this histone code to regulate the usage of the underlying DNA. In the maturing oocytes and eggs of the frog Xenopus laevis, histones are synthesized in bulk in preparation for deposition during the rapid early developmental cell cycles. During this key developmental time frame, embryonic pluripotent chromatin is established. In the egg, non-chromatin-bound histones are complexed with storage chaperone proteins, including nucleoplasmin. Here we describe the identification and characterization of a complex of the protein arginine methyltransferase 5 (Prmt5) and the methylosome protein 50 (Mep50) isolated from Xenopus eggs that specifically methylates predeposition histones H2A/H2A.X-F and H4 and the histone chaperone nucleoplasmin on a conserved motif (GRGXK). We demonstrate that nucleoplasmin (Npm), an exceedingly abundant maternally deposited protein, is a potent substrate for Prmt5-Mep50 and is monomethylated and symmetrically dimethylated at Arg-187. Furthermore, Npm modulates Prmt5-Mep50 activity directed toward histones, consistent with a regulatory role for Npm in vivo. We show that H2A and nucleoplasmin methylation appears late in oogenesis and is most abundant in the laid egg. We hypothesize that these very abundant arginine methylations are constrained to pre-mid blastula transition events in the embryo and therefore may be involved in the global transcriptional repression found in this developmental time frame.
Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461.
Carola
C
Wilczek
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904.
Raghu
R
Chitta
Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, New York 10065.
Eileen
E
Woo
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904.
Jeffrey
J
Shabanowitz
Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, New York 10065.
Brian T
BT
Chait
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904.
Donald F
DF
Hunt
Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461. Electronic address: david.shechter@einstein.yu.edu.
David
D
Shechter
D000818:Animals; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D016367:Baculoviridae / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D005822:Genetic Vectors; D006657:Histones / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008745:Methylation; D018832:Molecular Chaperones / Q000378:metabolism; D056489:Nucleoplasmins / Q000378:metabolism; D011484:Protein-Arginine N-Methyltransferases / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D018832:Molecular Chaperones; D056489:Nucleoplasmins; D029867:Xenopus Proteins; C570111:methylosome protein 50, Xenopus; D001120:Arginine; C495466:Prmt5 protein, Xenopus; D011484:Protein-Arginine N-Methyltransferases