Sammendrag
Protein methylation is a post-translational modification best studied in regards to histones and the histone code. In recent years, more studies have begun to unearth non-histone protein methylation, in most cases however, the responsible enzymes remain unidentified. Methylation of non-histone proteins could impart new characteristics, such as altering protein-protein interactions, stability, localization, and/or enzymatic activities. Recently, a novel family of ten lysine specific methyltransferases (KMTs) was identified, of which only a few have thus far been characterized. These include valosine-containing protein KMT (VCP-KMT) (Kernstock et al., 2012), calmodulin-KMT (Magnani et al., 2010) and heat shock protein 70-KMT (Hsp70-KMT)(Jakobsson et al., 2013). Characterization of the remaining members of this family, including methyltransferase like 20 (METTL20), would expand the knowledge of non-histone methyltransferases. In this study, data are presented that reveal the identity of two proteins in Agrobacterium tumefaciens (A. tumefaciens) that are substrates of the bacterial orthologue of METTL20. The sites of methylation for each substrate were ascertained by mutagenesis and fluorography. To elucidate the biological role of the bacterial orthologue of METTL20, a strain of A. tumefaciens was generated with a knockout (KO) of the METTL20 gene. Wild type (WT) and KO bacteria were subject to various growth conditions and stresses in an attempt to uncover a condition in which one strain outperformed the other in regards to viability and/or growth. A potential phenotype was discovered that could involve the viability and ability to grow under certain stress conditions.