Petidoglycan Synthesis Flashcards Preview

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Flashcards in Petidoglycan Synthesis Deck (13):

Whats the difference I. The amount of peptidoglycan content between g pos and g neg bacterial cell walls ?

G pos have about 90% peptidoglycan in their cell wall where as g beg have only about 5-10%.


What is found in the glycan portion of the molecule ?

This is the sugar portion and is the same across species. It forms the back bone and is comprised of N-acetylglucosamine (NAG) and N-acetylmeuramic acid (NAM). These alternate and are joined by glycosidic bonds.


What is the structure of the peptide portion of peptidoglycan ?

Amino acids connected by peptide linkages l, variations occur. Alternating d and l amino acids. These amino acids are attached to NAM units. Variations occur whenDAP is found.


How are single chains of peptidoglycan linked ?

Can either be peptide bridges or direct bridges.


How is NAG formed ?

Glucose> fructose-6-P>reacts with glutamate and acetyl-CoA> NAG


How is NAM formed ?

NAG + uridine triphosphate (UTP)> NAG-uridinediphosphate (UDP)>reacts with phosphoenolpyruvate> N-acetylmeramic acid-UDP> NAGM


what happens in stage 2 of the synthesis of PG ?

The UDP sugar links (made in step one) are then transferred to lipid carriers.


what is the NAM pentapeptide transferred to ?



what is bactoprenol- phosphate found as in the cm?

it is foun d as pyrophosphate and must be dephosphorylated before it can act a s a carrier.


What and how is NAG transferred ?

NAG is transferred to the NAM-bactoprenil-pentapeptide, creating NAG-NAM- bactoprenol pentapeptide.


What happens when NAG and NAM have been picked up by the carriers ?

PG subunits are released on to existing cell wall.


What is the final stage of PG synthesis ?

The formation of peptide linkages between adjacent glycan chains. Formed between exsisting cell and newly formed PG


What is the enzyme that makes the final peptide bonds ?