Bacterial membrane phospholipids and Gram-negative lipopolysaccharides (LPS and Phospholipids)

Bacterial membrane phospholipids and Gram-negative lipopolysaccharides (LPS) are fundamental structural elements of the bacterial cell envelope that serve as critical targets for several classes of antibiotics. Phospholipids, including phosphatidylglycerol and cardiolipin, constitute the cytoplasmic membrane in both Gram-positive and Gram-negative bacteria, providing a semi-permeable barrier and a matrix for membrane proteins (Epand et al., 2016). LPS is a unique glycolipid found in the outer leaflet of the Gram-negative outer membrane, where it acts as a robust physical barrier against toxic compounds and is a primary mediator of the host's inflammatory response via Toll-like receptor 4 (TLR4) (Maldonado et al., 2016). Drugs such as polymyxins (Colistin and Polymyxin B) specifically target the Lipid A component of LPS, while lipopeptides like daptomycin interact with membrane phospholipids in a calcium-dependent manner (Grein et al., 2020). These interactions lead to membrane depolarization, loss of cytoplasmic contents, and rapid bacterial cell death. This target entry is considered composite as it encompasses two distinct chemical classes that are functionally related in the context of antimicrobial therapy (StatPearls, 2023).

Other names

Bacterial cell envelopeEndotoxinLipid ABacterial cytoplasmic membraneOuter membrane lipids

Antibiotics target these molecules through electrostatic binding to negatively charged groups (such as the phosphate groups in Lipid A or phospholipids), leading to membrane displacement, pore formation, and depolarization of the bacterial cell membrane (StatPearls, 2023; Epand et al., 2016).