Figure 5.

Effect of lysine methylation on Sll0480 enzymatic activity

A. Schematic illustration of the metabolic pathway catalyzed by Sll0480. B. Western blot analysis of the methylation level of Sll0480 after incubation with CpcM and SAM using anti-Kme antibody. Samples were standardized through comparisons with Coomassie-blue-stained gel. The untreated Sll0480 (Sll0480+SAM) group and the heat-inactivated CpcM (represented by #) group were used as negative controls. SAM, S-adenosyl methionine. C. The densitometry analysis of methylated Sll0480 in the reactions from (B) using ImageJ software. D. List of identified methylated peptides from Sll0480 in the reactions from (B). The untreated Sll0480 (Sll0480+SAM) was used as a control, and the Sll0480 incubated with CpcM and SAM was tested. E. Representative MS/MS spectra of the methylated peptides in (D). A series of b-ions (green) and y-ions (red) were labeled in the spectra. F. Enzyme activity of Sll0480 after incubation with CpcM and SAM. The provided aspartate aminotransferase (AAT) in the kit was used as a positive control (PC), while the reactions without Sll0480 or heat-inactivated Sll0480 (represented by #) were used as negative controls. Data are presented as means ± SD from three independent experiments. The level of statistical significance was determined by two-sample Student’s t-test (**, P < 0.01).