peptidoglycan biosynthetic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of peptidoglycans, any of a class of glycoconjugates found in bacterial cell walls. [http://www.dsmz.de/species/murein.htm, ISBN:0198506732]

Peptidoglycan biosynthesis is a complex process that involves the assembly of a unique polymer called peptidoglycan, which forms the rigid, protective layer surrounding the cell wall of bacteria. This process is essential for bacterial survival and is a major target for antibiotics.

The synthesis of peptidoglycan involves a series of steps, including:

**1. Synthesis of building blocks:**

* **N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG):** These sugars are the building blocks of peptidoglycan and are synthesized separately. NAM is formed by the addition of a lactyl group to NAG.
* **Peptides:** Short chains of amino acids are synthesized and attached to NAM. The specific sequence of amino acids varies depending on the bacterial species.

**2. Assembly of the peptidoglycan precursor:**

* NAM and NAG are linked together to form a disaccharide unit.
* The peptide chain attached to NAM is extended by the addition of more amino acids.
* This disaccharide-peptide unit is then attached to a carrier molecule called undecaprenyl phosphate (Und-P), forming a lipid-linked precursor.

**3. Translocation across the membrane:**

* The lipid-linked precursor is transported across the bacterial cell membrane by a flippase enzyme.

**4. Incorporation into the peptidoglycan layer:**

* The lipid-linked precursor is incorporated into the growing peptidoglycan chain by a transglycosylase enzyme, which links the disaccharide units together.
* A transpeptidase enzyme then forms cross-links between the peptide chains attached to different NAM units, strengthening the peptidoglycan structure.

**5. Recycling of Und-P:**

* The carrier molecule, Und-P, is recycled for use in subsequent rounds of peptidoglycan synthesis.

**Regulation of peptidoglycan biosynthesis:**

* The synthesis of peptidoglycan is tightly regulated by a variety of mechanisms, including feedback inhibition, allosteric regulation, and the activity of specific regulatory proteins.

**Antibiotic targets:**

* Many antibiotics target peptidoglycan biosynthesis. For example, penicillin and its derivatives block the activity of transpeptidases, inhibiting the formation of cross-links between peptide chains. Vancomycin inhibits the incorporation of peptidoglycan precursors into the growing peptidoglycan chain.

**Conclusion:**

Peptidoglycan biosynthesis is a vital process for bacterial survival. It involves the synthesis and assembly of a unique polymer that forms the rigid cell wall. This process is a major target for antibiotics, making it a crucial area of research in the fight against bacterial infections.'
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Proteins (9)

Compounds (15)