Arabinosyltransferase (Emb) (Emb)

Arabinosyltransferases are essential enzymes in Mycobacterium tuberculosis responsible for the polymerization of D-arabinofuranose residues into the arabinan segments of the cell wall's arabinogalactan (AG) and lipoarabinomannan (LAM) (NIH, 2009; MDPI, 2023). These enzymes, primarily EmbA, EmbB, and EmbC, are large transmembrane proteins that utilize decaprenylphosphoryl-D-arabinose (DPA) as a sugar donor (NIH, 2020). In M. tuberculosis, these enzymes are critical for maintaining the structural integrity and permeability of the complex mycobacterial cell envelope, which is vital for survival and pathogenesis (NIH, 2009). The first-line antitubercular drug ethambutol targets these enzymes, specifically inhibiting EmbB and EmbC, which leads to the disruption of cell wall assembly and a bacteriostatic effect (Wikipedia, 2024; PatSnap, 2024). Resistance to ethambutol is frequently associated with mutations in the embB gene, highlighting the target's clinical significance (NIH, 2009; BenchChem, 2025). The inhibition of these enzymes increases the permeability of the cell wall, which can enhance the efficacy of other co-administered antitubercular agents (PatSnap, 2024).

Other names

Arabinosyl transferasesEmb proteinsArabinofuranosyltransferaseEmbAEmbBEmbCAftAAftBAftCAftDArabinosyltransferase AArabinosyltransferase BArabinosyltransferase C

Ethambutol inhibits the arabinosyltransferase enzymes (primarily EmbB and EmbC) by competing with the substrate decaprenylphosphoryl-D-arabinose (DPA), thereby blocking the polymerization of arabinose into the cell wall components arabinogalactan and lipoarabinomannan (NIH, 2009; PatSnap, 2024).