PagL, a lipid A deacylase, is unique in that it is latent in the outer membrane of Salmonella enterica serovar Typhimurium. Several point mutations in the extracellular loops of PagL, which do not affect its enzymatic activity, release it from this latency. Precipitation analysis revealed that latent wild-type PagL associated with lipopolysaccharide, but non-latent PagL mutants did not. In contrast, non-latent PagL mutants preferentially associated with some membrane proteins. Precipitation analysis using inactive PagL mutants demonstrated that membrane lipid A deacylation did not affect association. These results indicate that mutations in the lipid A deacylase PagL which relieve the enzyme from its latency affect the ability of PagL to interact with lipopolysaccharide. (c) 2010 Elsevier Inc. All rights reserved.