Which lipid component constitutes the cord factor in Mycobacterium tuberculosis?

Which lipid component constitutes the cord factor in Mycobacterium tuberculosis?

• A. Sulfatides
• B. Catalase-peroxidase (KatG)
• C. Trehalose dimycolate
• D. Mycolic acid

Answer: (C)

Cord factor is a virulence-associated glycolipid of Mycobacterium tuberculosis, best represented by trehalose dimycolate. This molecule consists of trehalose linked to two mycolic acids, and it drives the characteristic serpentine cord growth of virulent strains in culture. It also activates macrophages to release inflammatory cytokines like TNF-alpha, contributing to disease pathology. While mycolic acids are major cell-wall components and sulfatides are another class of mycobacterial lipids, only trehalose dimycolate is the cord factor. The enzyme KatG is a catalase-peroxidase, not a lipid, so it does not define the cord factor.

Cord factor is a virulence-associated glycolipid of Mycobacterium tuberculosis, best represented by trehalose dimycolate. This molecule consists of trehalose linked to two mycolic acids, and it drives the characteristic serpentine cord growth of virulent strains in culture. It also activates macrophages to release inflammatory cytokines like TNF-alpha, contributing to disease pathology. While mycolic acids are major cell-wall components and sulfatides are another class of mycobacterial lipids, only trehalose dimycolate is the cord factor. The enzyme KatG is a catalase-peroxidase, not a lipid, so it does not define the cord factor.