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. Author manuscript; available in PMC: 2022 Jun 1.
Published in final edited form as: Curr Opin Microbiol. 2021 Mar 1;61:16–24. doi: 10.1016/j.mib.2021.02.001

Figure 1: The cell envelope, including the peptidoglycan cell wall, is a complex structure that protects bacteria from the surrounding environment.

Figure 1:

A) Gram-positive bacteria have a single membrane surrounded by a thick layer of peptidoglycan (PG). Wall teichoic acids (WTAs) are attached covalently to PG, while lipoteichoic acids (LTAs) are anchored in the membrane. Gram-negative organisms have two membranes that sandwich a thin layer of peptidoglycan in the periplasm. The outer membrane (OM) contains outer membrane proteins (OMPs), as well as lipopolysaccharide on its outer leaflet. B) PG is synthesized by glycosyltransferases (GTs) that polymerize Lipid II and transpeptidases (TPs) that enact crosslinking. Hydrolases, including lysins, cleave PG at diverse positions.