Undecaprenyl Phosphate (UP)

Undecaprenyl phosphate (UP), also known as bactoprenol phosphate, C55-P, or lipid-P, is an essential polyisoprene lipid carrier molecule found in bacteria. It plays a central role in the biosynthesis and transport of cell wall polysaccharides, most notably peptidoglycan, across the cytoplasmic membrane. UP acts as a membrane-bound carrier that ferries activated sugar precursors from the cytoplasm to the periplasmic side of the bacterial inner membrane during peptidoglycan synthesis. After delivering its cargo, UP is recycled through cycles of phosphorylation and dephosphorylation for reuse in subsequent rounds of cell wall synthesis. Inhibition or sequestration of UP disrupts peptidoglycan synthesis leading to rapid bacteriolysis.

Other names

Bactoprenol phosphateC55-PLipid-PUnd-P

Bacitracin binds tightly to undecaprenyl pyrophosphate, blocking its conversion back into usable UP. Amphomycin inhibits protein-mediated flipping/recycling functions associated with C55-P/UPT-A interactions.