Undecaprenyl phosphate (C55-P)

Undecaprenyl phosphate, also known as bactoprenyl phosphate, is an essential C55 isoprenoid lipid that functions as a membrane-bound carrier in bacteria (Source: PubMed, PMID: 16299104). Its primary role is to transport hydrophilic precursors of the cell wall, such as peptidoglycan subunits (Lipid II), across the cytoplasmic membrane to the site of assembly (Source: Nature, doi:10.1038/nature14098). This lipid carrier is recycled through a cycle of phosphorylation and dephosphorylation; specifically, undecaprenyl pyrophosphate must be converted back to undecaprenyl phosphate to initiate a new round of transport (Source: JBC, doi:10.1074/jbc.M110.155010). This recycling process is the target of the antibiotic bacitracin, which forms a complex with the pyrophosphate form in the presence of divalent cations, thereby halting cell wall synthesis and leading to bacterial cell death (Source: StatPearls, NBK536977). Because the undecaprenyl phosphate cycle is unique to prokaryotes and vital for maintaining structural integrity, it is a highly validated target for the development of narrow and broad-spectrum antibacterial agents. Newer antibiotics like teixobactin also interact with this pathway by binding to the lipid-linked precursors, effectively sequestering the carrier and preventing its reuse (Source: Nature, doi:10.1038/nature14098). The essentiality of this carrier across diverse bacterial species makes it a resilient target against the development of resistance, as seen with the slow emergence of resistance to drugs like teixobactin.

Other names

Bactoprenyl phosphateUndecaprenyl pyrophosphateC55-isoprenyl phosphateLipid carrierC55-PP

Inhibition of lipid carrier recycling by binding to undecaprenyl pyrophosphate and preventing dephosphorylation (e.g., Bacitracin), or by sequestering the lipid carrier to prevent precursor loading (e.g., Friulimicin B).