Structural insight into arginine methylation by the mouse protein arginine methyltransferase 7: a zinc finger freezes the mimic of the dimeric state into a single active site

Protein arginine methyltransferase 7 (PRMT7) is a type III arginine methyltransferase which has been implicated in several biological processes such as transcriptional regulation, DNA damage repair, RNA splicing, cell differentiation and metastasis. PRMT7 is a unique but less characterized member of the family of PRMTs. The crystal structure of full‐length PRMT7 from Mus musculus refined at 1.7 Å resolution is described. The PRMT7 structure is composed of two catalytic modules in tandem forming a pseudo‐dimer and contains only one AdoHcy molecule bound to the N‐terminal module. The high‐resolution crystal structure presented here revealed several structural features showing that the second active site is frozen in an inactive state by a conserved zinc finger located at the junction between the two PRMT modules and by the collapse of two degenerated AdoMet‐binding loops.