Fig. 3: Characterization of the biosynthetic pathway.
a, Proposed biosynthetic route for the Dmp modified C-terminus. b, MALDI-TOF mass spectra of IMAC-purified MpaA1 that were co-expressed with the indicated Mpa biosynthetic proteins in E. coli (4, m/z 5872; 5, m/z 5826; 6, m/z 5827; 7, m/z 5855). c, Enlarged MALDI-TOF mass spectra of mpaABCD, mpaABCM, and mpaABC co-expressions in panel b. d, Carbonyl reactivity using aminooxy probe 8. e, MALDI-TOF MS results for the unmodified peptide 4 and ketone intermediate 5 (oxime 9, m/z 5931).