Arabinosyltransferase (None established; sometimes abbreviated as "Aft" for specific isoforms (e.g., AftA, AftC) in mycobacteria)

Arabinosyltransferases are membrane-bound glycosyltransferase enzymes that catalyze the transfer of arabinose residues, typically from decaprenylphosphoryl-arabinose donors onto acceptor molecules such as galactan chains. In mycobacteria, they are essential components responsible for building complex polysaccharides like arabinogalactan and lipoarabinomannan, which form critical parts of the unique mycobacterial cell envelope—a structure vital both for bacterial viability and pathogenicity. The best-characterized members include several isoforms such as AftA, which initiates attachment of the first arabinan residue during polymer assembly; other isoforms introduce branch points or extend chains further along biosynthetic pathways. These enzymes are also found across plant species where they participate in modifying secondary metabolites important for disease resistance. In medicine, particularly infectious disease therapeutics against tuberculosis, these enzymes represent validated drug targets—most notably inhibited by ethambutol. Inhibition disrupts cell wall formation leading to bacteriostasis or death. Technical challenges remain regarding assay development due to their membrane association and substrate requirements but ongoing structural studies continue to inform new inhibitor design strategies.

Other names

Arabinofuranosyltransferase (more precise for mycobacterial enzymes)AftA, AftB, AftC (isoforms in mycobacteria)ARAD proteins (in plants)

Ethambutol inhibits the transfer of arabinose residues during the polymerization of arabinogalactan/lipoarabinomannan by binding to membrane-bound arabinosyltransferases, thereby disrupting cell wall synthesis and leading to bacterial death or stasis