A Quick Review of the Bacterial Cell Wall Structure
Imagine modified from (Funahara, Y., Nikaido, H., 1980. Asymmetric localization of lipopolysaccharides on the outer membrane of Salmonella typhimurium. J. Bacteriol. 141, 1463–65.; Nikaido, H., 2003. Molecular basis of bacterial outer membrane permeability revisited. Microbiol. Mol. Biol. Rev. 67, 593–656.)
Gram-Positive Bacteria <1>
Gram-positive bacteria cell walls are primarily composed of peptidoglycan. Peptidoglycans are made up of glycan chains cross-linked by peptide chains. Peptidoglycans synthesis involves enzymes called penicillin binding proteins (PBPs). Some antibiotics are able to block PBPs to disrupt bacterial cell wall formation.
Gram-Negative Bacteria <1>
Gram-negative bacteria cell walls contain a smaller proportion of peptidoglycan compared to gram-positive bacteria. Compared to gram-positive bacteria, gram-negative cell walls contain three additional components outside its peptidoglycan layer. These include the lipoprotein, outer membrane, and lipopolysaccharide (LPS). The outer membrane creates an impermeable barrier. Nutrients are shuttled into the cell through structural proteins called porins. Porins are used by some antibiotics as entry points into the bacterial cell.
References:
1. Mandell GL, Bennett JE, Dolin R. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. 9th ed. Philadelphia: Churchill Livingstone/Elsevier; 2009.
1. Mandell GL, Bennett JE, Dolin R. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. 9th ed. Philadelphia: Churchill Livingstone/Elsevier; 2009.