Antigen 85 complex A from Mycobacterium tuberculosis (Ag85A)

Antigen 85 complex A (Ag85A) from Mycobacterium tuberculosis is a major secreted mycolyl-transferase enzyme essential for the biosynthesis of the mycobacterial cell wall. It is one member (alongside Ag85B and Ag85C) of the antigen 85 complex, encoded by separate genes but highly homologous. Ag85A catalyzes the transfer of mycolic acids from trehalose monomycolate to other cell wall components, a process vital for cell envelope integrity and viability of M. tuberculosis. It is one of the most abundant and immunogenic proteins secreted by the bacterium, acts as a fibronectin-binding protein (conferring adhesion properties), and is a key biomarker for tuberculosis infection. Because of its central role in cell wall synthesis and secretion (increasing drug target accessibility), it is regarded as a promising therapeutic target for tuberculosis drug development and vaccine design[1][2][3][5]. Drugs such as ebselen have shown activity against Ag85 enzymes by inhibiting their catalytic site, making Ag85A an active focus in the development of new antitubercular therapies, especially in drug-resistant cases[1][5].

Other names

Antigen 85AAg85A30-kDa proteinMycolyl-transferase Ag85AFibronectin-binding protein A

Inhibition of acyltransferase/mycolyl-transferase activity, blocking mycolic acid transfer and disrupting cell wall biosynthesis[1][5] - Direct covalent binding to catalytically essential cysteine residues alters enzymatic function[1]