Mycobacterial cell envelope glycans and peptidoglycan (mAGP complex) (mAGP complex)

The mycobacterial cell envelope is a complex, multi-layered structure characterized by a unique core known as the mycolyl-arabinogalactan-peptidoglycan (mAGP) complex (Brennan, 2003). This structure consists of a peptidoglycan layer covalently linked to a branched arabinogalactan polysaccharide, which is in turn esterified to long-chain mycolic acids. These components provide the bacterium with exceptional structural integrity and create a formidable hydrophobic permeability barrier against many common antibiotics (Abrahams & Besra, 2018). Beyond structural support, glycans like lipoarabinomannan (LAM) play critical roles in modulating the host immune response and facilitating intracellular survival within macrophages (Kaur et al., 2009). Because these pathways are essential for viability and unique to mycobacteria, they serve as the primary targets for first-line anti-tuberculosis drugs such as isoniazid and ethambutol. Disrupting the synthesis or assembly of these glycans and peptidoglycan leads to cell lysis and is a cornerstone of treatment for infections caused by Mycobacterium tuberculosis and other pathogenic mycobacteria. Recent therapeutic strategies also focus on inhibiting the L,D-transpeptidases responsible for peptidoglycan cross-linking, which are distinct from those in other bacteria. The complexity of this target necessitates multi-drug regimens to prevent the emergence of resistance and ensure complete eradication of the pathogen.

Other names

Mycolyl-arabinogalactan-peptidoglycan complexMycobacterial cell wallmAGPLipoarabinomannanArabinogalactan-peptidoglycan complex

Inhibition of mycolic acid biosynthesis, inhibition of arabinosyltransferase enzymes, and inhibition of peptidoglycan cross-linking (Abrahams & Besra, 2018).