Arabinosyltransferase B (EmbB) (EmbB)

Arabinosyltransferase B (EmbB) is a vital membrane-bound enzyme in Mycobacterium tuberculosis responsible for the polymerization of the arabinan segments of the mycobacterial cell wall (UniProt P9WNJ1). It works in conjunction with EmbA and EmbC to synthesize arabinogalactan and lipoarabinomannan, which provide structural integrity and protection to the bacterium. EmbB is the primary molecular target of ethambutol, a cornerstone of first-line tuberculosis treatment. By inhibiting EmbB, ethambutol disrupts cell wall assembly, leading to increased bacterial susceptibility and death (Zhang et al., 2020, Science). However, the emergence of resistance due to specific mutations in the embB gene, particularly at the Met306 residue, remains a significant clinical challenge (Telenti et al., 1997, Nature Medicine). Understanding the structural and functional aspects of EmbB is crucial for developing next-generation antitubercular agents that can overcome existing resistance mechanisms.

Other names

EmbBArabinosyltransferase EmbBProbable arabinosyltransferase BEthambutol-sensitive arabinosyltransferaseRv3795

Ethambutol acts as a competitive inhibitor of the arabinosyltransferase enzyme, specifically targeting the EmbB and EmbA subunits. It prevents the transfer of arabinose from the donor decaprenyl-phospho-arabinose (DPA) to the growing arabinan chain, thereby disrupting the synthesis of arabinogalactan and lipoarabinomannan, which are essential components of the mycobacterial cell wall (Zhang et al., 2020, Science).