FIGURE 4.

Trmt61B is responsible for m¹A formation in E. coli cells. (A) LC/MS analysis of total tRNA nucleosides from E. coli rosetta cells (top panel) and His-Trmt61B–expressing E. coli rosetta strain (middle panel). Mass chromatograms detecting MH⁺ (m/z 282) of m¹A, Am, m²A, and m⁶A are shown. Synthetic nucleosides (m¹A, Am, and m⁶A) were also analyzed as a control (bottom panel). (B) Purified His-Trmt61B was resolved by SDS-PAGE and stained with Coomassie brilliant blue. The protein size marker is indicated. (C) Elution profile (UV trace at 280 nm) of His-Trmt61B (bottom) with protein size marker (top) in gel filtration chromatography.