FIGURE 6.

Mass spectrometric identification of non-glycosylated peptides from PilA1 and PilA2 in the ΔaglB strain. Peptides of GluC-digested proteins from CsCl density gradients obtained from cells from the ΔaglB strain were analyzed by MS using HCD fragmentation. Consistent with the peptides containing AglB-dependent glycosylation, only the non-glycosylated peptides NNSAGASSGDGVQGDVLKITHE (A, precursor m/z 719.68, charge 3) from PilA1 as well as ITAGSSITVTANGSSFDSGE (B, precursor m/z 950.94, charge 2) and TSPQASFDFDYTNTSGNLTITHE (C, precursor m/z 1427.86, charge 3) from PilA2 were identified. The observed b-ions (red) and y-ions (blue) are indicated in the presented MS2 spectra as well as the fragmentation scheme (n = 2).