Arabinosyltransferase (EmbA, EmbB, and EmbC) (Emb)

Arabinosyltransferases are essential enzymes in Mycobacterium tuberculosis that catalyze the polymerization of D-arabinofuranose into the arabinan domains of the mycobacterial cell wall. This enzyme family, comprising EmbA, EmbB, and EmbC, utilizes decaprenyl-phospho-arabinose as a sugar donor to build the arabinogalactan and lipoarabinomannan layers (Zhang et al., 2020, Science). Arabinogalactan is a core structural component that tethers the peptidoglycan to the outer mycolic acid layer, while lipoarabinomannan plays a significant role in modulating the host immune response during infection (Goude et al., 2009, Journal of Bacteriology). Because these enzymes are vital for maintaining the integrity of the mycobacterial cell envelope, they are critical targets for antimicrobial intervention. The first-line antitubercular drug ethambutol exerts its bactericidal effect by inhibiting these arabinosyltransferases, specifically targeting the EmbB and EmbA subunits (Telenti et al., 1997, Nature Medicine). Disruption of this pathway leads to increased cell wall permeability and eventual bacterial death. Resistance to ethambutol is frequently associated with specific mutations in the embB gene, highlighting the enzyme's importance in clinical outcomes (Safi et al., 2013, Nature Communications).

Other names

EmbAEmbBEmbCArabinosyltransferase AArabinosyltransferase BArabinosyltransferase CMycobacterium tuberculosis arabinosyltransferase complexEmbCAB complex

Inhibition of the transfer of arabinose units from the donor decaprenyl-phospho-arabinose to the cell wall acceptor, disrupting the assembly of the arabinogalactan and lipoarabinomannan layers.