Bacterial cell wall arabinosyltransferase enzyme

The bacterial cell wall arabinosyltransferase enzyme is a membrane-bound glycosyltransferase essential for the biosynthesis of complex carbohydrates in the mycobacterial cell envelope. This family includes enzymes such as AftA and the Emb proteins (EmbA, EmbB, EmbC), which are responsible for transferring arabinose residues—specifically in their furanose form—to growing polysaccharide chains like arabinogalactan and lipoarabinomannan. These polymers are critical structural components that confer impermeability to the mycobacterial outer membrane, contributing significantly to pathogenicity and resistance against antibiotics. Arabinosyltransferases are unique to Actinobacteria such as Mycobacterium tuberculosis. They have been structurally characterized as having a conserved GT-C fold. The clinical significance of these enzymes is underscored by their role as targets for anti-tuberculosis drugs like ethambutol; inhibition disrupts proper assembly of the protective cell envelope, making bacteria susceptible to environmental stressors and immune attack. Resistance mutations often occur near drug binding sites but typically preserve essential enzymatic function.

Other names

ArabinosyltransferaseArabinofuranosyltransferaseMycobacterial arabinosyltransferaseEmb proteins (e.g., EmbA, EmbB, EmbC)AftA (a specific priming arabinosyltransferase)

Inhibition of the enzyme by ethambutol blocks the addition of arabinose units to cell wall polysaccharides, disrupting cell wall synthesis and leading to bacterial death or growth inhibition.