SAH is the coproduct of the transmethylation reaction requiring S-adenosylmethionine (SAM). Generation of SAH accompanies the facile transfer of the activated methyl group of SAM to a variety of recipient molecules such as proteins, RNA, DNA, and polysaccharides, as well as small molecules such as phospholipids, histamines, norepinephrine, and catecholamines (Chiang et al., 1996; Fernandez-Sanchez et al., 2009). In the pathway of intracellular methylation metabolism, adenosine can be deaminated Selleck Ivacaftor to inosine by adenosine deaminase or enters the purine nucleotide pool by the action of adenosine kinase (Ak). SAM is derived from an ATP-dependent

transfer of adenosine to methionine, catalyzed by methionine adenosyltransferase (MAT; Kloor & Osswald, 2004). The SAM-dependent O-methyltransferases (OMTs) regulate the O-methylation of various secondary metabolites, such as the flavonoids 6,7-dihydroxyflavone, quercetin, and 7,8-dihydroxyflavone, BIBW2992 order as well as phenolic compounds, such as caffeic acid and caffeoyl Co-A. Many diseases have been found to be associated with changes in SAHH function. For instance, deficiency of SAHH is associated with cardiovascular disease in human and animals (Zaina et al., 2005; Matthews et al., 2009). The mRNA level of SAHH is found

to be significantly decreased in human tumors (Leal et al., 2008). The oncogenic transcription factor Myc induces methyl-cap formation by promoting phosphorylation of RNA polymerase II and increasing the SAHH activity

(Cowling, 2010). Recent studies reveal that inhibitors of SAHH catalysis have multiple pharmacologic functions, including anticancer, antivirus, and antiparasite (Bray et al., 2000; Nakanishi, 2007; Cai et al., 2009; Sun et al., 2009). As the key enzyme of methylation metabolism, SAHH regulates phosphatidylcholine synthesis and triacylglycerol homeostasis. Deletion of the gene encoding SAHH changes the level of phosphatidylcholine and triacylglycerol in Saccharomyces cerevisiae (Tehlivets et al., 2004; Malanovic et al., 2008). However, the role of SAHH in pathogenic fungi has not been reported. Chestnut blight fungus (Cryphonectria parasitica) is a filamentous fungus responsible for the chestnut blight disease. Sahh transcription was found to be upregulated in a hypovirus-infected C. parasitica mafosfamide strain using a microarray hybridization (Allen et al., 2003). The purpose of the current study was to gain more insight into the role of SAHH protein for the virulence of chestnut blight fungus. Here, we expressed in vitro and knocked out the sahh gene and identified the molecular, biochemical, and biological characterization of the SAHH protein in C. parasitica. Cryphonectria parasitica wild-type strain EP155 (ATCC38755), its isogenic strain EP713 (ATCC52571) that harbors hypovirus CHV1-EP713, strain CP80 (ΔKU80 of EP155; Lan et al.