Bacterial cell envelope and periplasmic structures

The bacterial cell envelope is a complex, multi-layered structure that serves as the primary interface between a bacterium and its environment, providing essential protection and structural integrity [Silhavy et al., 2010]. In Gram-negative bacteria, this structure consists of the inner cytoplasmic membrane, a thin peptidoglycan layer within the aqueous periplasmic space, and an asymmetric outer membrane [Ruiz et al., 2006]. Gram-positive bacteria lack an outer membrane but possess a significantly thicker peptidoglycan layer interspersed with teichoic acids. This envelope is critical for maintaining osmotic pressure and regulating the influx of nutrients and efflux of waste products through specialized proteins like porins [Miller, 2016]. Because many components of the cell envelope, such as peptidoglycan and lipopolysaccharides, are unique to bacteria, they represent highly effective targets for antibiotics. Drugs like beta-lactams and glycopeptides interfere with the assembly of the cell wall within the periplasm, leading to osmotic lysis and cell death [Kohanski et al., 2010]. However, the envelope also serves as a major barrier to drug entry, and modifications to its structure are a primary mechanism of antibiotic resistance in clinical settings.

Other names

Bacterial cell wallCell envelopePeriplasmPeriplasmic spaceBacterial boundary

Inhibition of peptidoglycan cross-linking by binding to penicillin-binding proteins (PBPs), disruption of the outer membrane through displacement of divalent cations in lipopolysaccharides, and inhibition of the transport of cell wall precursors across the cytoplasmic membrane [Kohanski et al., 2010; Silhavy et al., 2010].