Figure 3

Trichomonas vaginalis lateral gene transfer (LGTs) that are potentially involved in glycan metabolism. (a) Schematic overview of the structures of a typical N-glycan and the enzymes (EC numbers in black delineated boxes) that can degrade them, according to the KEGG pathway ec00511. A typical O-glycan (extended core 1) [79] is also illustrated, along with selected enzymes shared with N-glycan degradation. O-glycans are the major glycans found in mucins, which are degraded by T. vaginalis. The characteristic components of glycans are shown. NeuNAc, N-acetylneuraminic acid; Gal, galactose; GlcNAc, N-acetylglucosamine; Man, Mannose; GalNac, N-acetylgalactosamine (O-glycan specific). The activities of six glycosidases originating form LGTs, out of a total of nine required to degrade N-glycans/gangliosides, are indicated by violet arrows, with their respective EC numbers in pink boxes. Two additional enzymes (EC numbers in orange boxes), N-acetylneuraminate lyase and acylglucosamine 2-epimerase, which also correspond to LGTs, could contribute to the further metabolism of the sugars liberated during glycan degradation. (b) Enzyme names and activities and evidence for LGT. Enzymes shared with the pathway for gangliosides metabolism are indicated. The final step of the degradation of gangliosides by a glucosylceramidase (EC:3.2.1.45) is also an LGT into T. vaginalis. The structure of gangliosides and the enzymes processing them are also illustrated (see Additional file 16).