Histone Methyltransferases in Aspergillus nidulans: Evidence for a Novel Enzyme with a Unique Substrate Specificity
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- 作者：Patrick Trojer ; Markus Dangl ; Ingo Bauer ; Stefan Graessle ; Peter Loidl ; and Gerald Brosch
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：August 24, 2004
- 年：2004
- 卷：43
- 期：33
- 页码：10834 - 10843
- 全文大小：155K
- 年卷期：v.43,no.33(August 24, 2004)
- ISSN：1520-4995
文摘
We have studied enzymes involved in histone arginine methylation in the filamentous fungusAspergillus nidulans. Three distinct protein arginine methyltransferases (PRMTs) could be identified,which all exhibit intrinsic histone methyltransferase activity when expressed as glutathione S-transferase(GST) fusion proteins. Two of these proteins, termed RmtA (arginine methyltransferase A) and RmtC,reveal significant sequence homology to the well-characterized human proteins PRMT1 and PRMT5,respectively. Native as well as recombinant RmtA is specific for histone H4 with arginine 3 as themethylation site. Furthermore, methylation of histone H4 by recombinant RmtA affects the acetylationby p300/CBP, supporting an interrelation of histone methylation and acetylation in transcriptional regulation.The second methyltransferase, named RmtB, is only distantly related to human/rat PRMT3 and must beconsidered as a member of a separate group within the PRMT family. The 61 kDa protein, expressed asa GST fusion protein, exhibits a unique substrate specificity in catalyzing the methylation of histones H4,H3, and H2A. Unlike human PRMT3, the Aspergillus enzyme lacks a Zn-finger domain in the amino-terminal part indicating functional differences of RmtB. Furthermore, phylogenetic analysis indicatedthat RmtB together with other fungal homologues is a member of a separate group within the PRMTproteins. The existence of in vivo arginine methylation on histones as demonstrated by site-specificantibodies and the high level and specificity of PRMTs for individual core histones in A. nidulans suggestsan important role of these enzymes for chromatin modulating activities.