Lipopolysaccharide lipid A phosphate groups

Lipid A phosphate groups are essential anionic components of the lipopolysaccharide (LPS) molecule found in the outer membrane of Gram-negative bacteria (Raetz et al., 2007, PubMed: 17589885). These phosphate groups, typically located at the 1 and 4' positions of the glucosamine backbone, provide a negative charge that is crucial for stabilizing the outer membrane through the bridging of divalent cations like calcium and magnesium (Nikaido, 2003, PubMed: 12730534). Biologically, they are recognized by the TLR4/MD-2 receptor complex in humans, triggering a potent inflammatory response that can lead to sepsis and septic shock (Park et al., 2009, PubMed: 19915566). From a therapeutic perspective, these phosphate groups serve as the primary binding site for cationic antimicrobial peptides and polymyxin antibiotics, such as colistin and polymyxin B (Velkov et al., 2013, PubMed: 24122106). Drugs target these groups via electrostatic interactions, which displaces stabilizing cations and leads to membrane disruption and bacterial cell death (Trimble et al., 2016, PubMed: 27530111). However, bacteria can develop resistance by modifying these phosphate groups with moieties like phosphoethanolamine or 4-amino-4-deoxy-L-arabinose, reducing the overall negative charge and drug affinity (Liu et al., 2016, PubMed: 26603172). This target is also a focus for the development of endotoxin-neutralizing agents designed to treat sepsis by preventing LPS from binding to host receptors (Matsuura, 2013, PubMed: 23435152).

Other names

Lipid A phosphateLPS phosphate groups1-phosphate and 4'-phosphate of lipid A

Electrostatic binding to negatively charged phosphate groups, displacing divalent cations and disrupting the bacterial outer membrane.