Recombinant vSET (A612L) protein
Recombinant vSET is suitable for use in histone methyltransferase (HMT) assays. Recombinant vSET protein was expressed in E. coli and contains an N-terminal His tag (MW=13 kDa). vSET is a viral protein encoded by paramecium bursaria chlorella virus 1 (PBCV-1), and has explicit methyltransferase activity for host histone H3 lysine 27. It has been shown that vSET can exert its activity by mimicking the function of EZH proteins of the mammalian Polycomb Repressive Complex 2 (PRC2) that are the only histone methyltransferases (HMTs) known to methylate H3K27. In contrast to mammalian HMTs that are monomeric and require binding partners for optimal methyltransferase activity, vSET functions as a dimer. It has been shown that vSET alone is required for global methylation of H3K27, unlike mammalian EZH2 HMT that is only capable of global H3K27 methylation in the context of the Polycomb Repressive Complex. vSET catalyzes H3K27 dimethylation and, to a lesser extent, mono- and trimethylation. It exerts activity on both free and nucleosome-associated H3.