Fig. 1.

Function of Mtb AftA. (A) Schematic representation of the components and assembly of the Mtb cell wall. (B) Biosynthesis of Mtb AG. AftA catalyzes the transfer of the first arabinosyl residue from donor DPA to the galactan chain, followed by elongation and branching steps catalyzed by EmbA–EmbB and AftC, AftB, and possibly AftD. (C) Cell-free-based arabinosyltransferase activity of purified Mtb AftA, using DPA and synthetic galactan acceptor analogs ( LG2–LG8). The enzymatic activity was monitored by the transfer of arabinofuranose to the C-5 position of the sixth galactofuranosyl residue of LG8 as reported previously (19, 20). The arabinofuranosyl residue is colored in red.