Cell envelope antibiotic

Cell envelope antibiotic is a type of antibiotic that targets the cell envelope of bacteria. The cell envelope is a protective layer that surrounds the bacterial cell, providing a barrier against harmful substances and maintaining the shape and integrity of the cell. Cell envelope antibiotics work by disrupting the structure or function of this envelope, leading to bacterial death.

Structure of the Cell Envelope

The cell envelope is composed of several layers, including the cell wall, the cell membrane, and, in some bacteria, an outer membrane. The composition and structure of these layers can vary widely among different types of bacteria, which can affect their susceptibility to different antibiotics.

Cell Wall

The cell wall is a rigid layer that provides structural support to the cell. In bacteria, it is typically composed of a complex molecule called peptidoglycan, which is a target of many cell envelope antibiotics.

Cell Membrane

The cell membrane, also known as the plasma membrane, is a semi-permeable layer that controls the movement of substances into and out of the cell. It is composed of a lipid bilayer, with proteins embedded within it.

Outer Membrane

Some bacteria, particularly Gram-negative bacteria, have an additional outer membrane. This membrane provides an extra layer of protection and can make these bacteria more resistant to antibiotics.

Mechanism of Action of Cell Envelope Antibiotics

Cell envelope antibiotics work by interfering with the synthesis or function of the cell envelope. This can occur in several ways:

• Inhibition of peptidoglycan synthesis: Some antibiotics, such as penicillin, work by preventing the synthesis of peptidoglycan, thereby weakening the cell wall and causing the cell to burst.

• Disruption of the cell membrane: Other antibiotics, such as polymyxin, work by binding to the cell membrane and disrupting its structure, leading to leakage of cell contents and cell death.

• Inhibition of outer membrane function: Some antibiotics, such as colistin, work by binding to the outer membrane and disrupting its function, making the cell more susceptible to other antibiotics.

Resistance to Cell Envelope Antibiotics

Bacteria can develop resistance to cell envelope antibiotics through several mechanisms, including modification of the cell envelope to prevent antibiotic binding, production of enzymes that degrade the antibiotic, and efflux pumps that expel the antibiotic from the cell.

See Also

• Antibiotic resistance
• Bacterial cell structure
• Mechanisms of antibiotic action