Members of this family are enzymes catalyzing the removal of the fatty acyl chain from the 3^rd position of lipid A, the highly conserved lipid moiety of the lipopolysaccharide (LPS), which is one of the main constituents of the Gram-negative bacterial outer membrane. The first identified member of the family was the outer membrane-localized lipid A 3-O-deacylase, which is encoded by the PagL gene of Salmonella enterica serovar typhimurium. Homologs have been discovered in a variety of Gram-negative bacteria, although the overall sequence similarity is rather low. When expressed in Escherichia coli and upon deacylation by PagL, lipid A underwent another modification, which was the result of the activity of the endogenous palmitoyl-transferase PagP. A conserved histidine-serine couple was identified as the active site suggesting a catalytic mechanism similar to serine hydrolases. The exact biological function of PagL remains unclear, while its high-resolution structure revealed a dimeric structure with ß-barrels comprising 8 transmembrane strands.

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