Bacterial phosphatidylglycerol-rich cell membrane (PG-rich membrane)

The bacterial phosphatidylglycerol-rich cell membrane is a critical structural and functional barrier that distinguishes prokaryotic cells from eukaryotic ones (Malanovic & Lohner, 2016, Biochim. Biophys. Acta). Unlike mammalian membranes, which are predominantly composed of neutral phospholipids like phosphatidylcholine, bacterial membranes contain high proportions of anionic lipids, most notably phosphatidylglycerol (PG) (Epand et al., 2016, Biochim. Biophys. Acta). This high negative charge density serves as a primary docking site for various cationic antimicrobial peptides and lipopeptide antibiotics (Hancock & Sahl, 2006, Nat. Biotechnol.). These therapeutic agents exploit the electrostatic difference to selectively target bacteria while sparing host cells. Upon binding, these drugs often insert into the lipid bilayer, causing physical disruption, pore formation, or depolarization of the membrane (Taylor & Palmer, 2016, Front. Org. Synth. Chem.). Such actions compromise the cell's ability to maintain essential ion gradients, leading to the cessation of vital metabolic processes and ultimately resulting in rapid bacterial cell death. This target is particularly significant in the treatment of multidrug-resistant Gram-positive infections, such as those caused by Methicillin-resistant Staphylococcus aureus (MRSA) (Bayer et al., 2013, Ann. N. Y. Acad. Sci.).

Other names

Bacterial cytoplasmic membraneAnionic bacterial membranePhosphatidylglycerol-containing bacterial membraneBacterial lipid bilayer

Drugs targeting this membrane typically utilize electrostatic attraction to the anionic phosphatidylglycerol headgroups. For example, daptomycin undergoes a calcium-dependent conformational change that allows it to insert into the PG-rich bilayer (Müller et al., 2016, Nat. Commun.). This insertion leads to membrane depolarization, leakage of intracellular ions like potassium, and the subsequent arrest of DNA, RNA, and protein synthesis, resulting in rapid bactericidal activity (Silverman et al., 2003, Antimicrob. Agents Chemother.).