Bacterial cytoplasmic membrane (Gram-positive) (BCM)

The bacterial cytoplasmic membrane of Gram-positive bacteria is a vital phospholipid bilayer that serves as the primary barrier between the cytoplasm and the external environment (Epand et al., 2016). Unlike Gram-negative bacteria, Gram-positive organisms lack an outer membrane, making their cytoplasmic membrane directly accessible to various antimicrobial agents once they penetrate the thick peptidoglycan layer. This membrane is rich in anionic lipids, such as phosphatidylglycerol and cardiolipin, which provide a target for cationic lipopeptides and antimicrobial peptides (Yeaman & Yount, 2003). It plays a critical role in essential cellular processes, including the generation of the proton motive force for ATP production, nutrient transport, and the anchoring of enzymes involved in cell wall biosynthesis (Strahl & Hamoen, 2010). Therapeutic agents like daptomycin exploit the membrane's composition by inserting into the bilayer in a calcium-dependent manner, leading to oligomerization, pore formation, and rapid depolarization that halts bacterial metabolism (Silverman et al., 2003). Because the integrity of this membrane is fundamental to bacterial viability, it remains a high-priority target for treating multi-drug resistant infections, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) (Heidary et al., 2018).

Other names

Bacterial plasma membraneGram-positive inner membraneProtoplast membraneCytoplasmic membrane

Antibiotics targeting the Gram-positive cytoplasmic membrane typically function by inducing rapid depolarization through ion leakage (e.g., potassium efflux), forming transmembrane pores, or binding to membrane-bound lipid intermediates like Lipid II to simultaneously disrupt membrane integrity and inhibit cell wall synthesis (Silverman et al., 2003; Ling et al., 2015).