Fig 2.

Methylation of recombinant Cren7 proteins by aKMT. (A) MALDI-TOF MS spectrum of the recombinant S. solfataricus Cren7 protein methylated by aKMT in vitro. Recombinant Cren7 was incubated with recombinant aKMT in the presence of SAM and analyzed by MALDI-TOF MS. Methylated lysine residues are labeled. (B) MALDI-TOF MS spectrum of the recombinant S. islandicus Cren7 protein coproduced with aKMT in E. coli. Genes encoding Cren7 and aKMT from S. islandicus were coexpressed in E. coli. The recombinant Cren7 was purified and subjected to MALDI-TOF MS. Molecular masses (as the mass/charge ratio) for peaks corresponding to unmethylated Cren7 (Um) and Cren7 containing one, two, and three methylated lysine residues are indicated. (Insets) Methylated lysine residues in the partial amino acid sequences of Cren7 are labeled.