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Discovery and purification of AaLpxE, a bi‐functional lipid phosphatase from Aquifex aeolicus
Author(s) -
Gillespie Robert A,
York John D,
Raetz Christian R H
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.787.4
Subject(s) - aquifex aeolicus , phosphatase , lipid a , biochemistry , phosphatidylglycerol , lipid ii , biology , phosphate , alkaline phosphatase , enzyme , phospholipid , chemistry , bacteria , escherichia coli , membrane , biosynthesis , gene , genetics , phosphatidylcholine
In Gram‐negative bacteria, highly immunogenic lipopolysaccharide is anchored to the outer membrane by the bisphosphorylated saccharolipid lipid A. In some bacterial species, the phosphate at the 1‐position is removed by LpxE, a dedicated, integral membrane lipid A 1‐phosphatase. Removal of the 1‐phosphate from lipid A greatly reduces host inflammatory response and coverts lipid A into a powerful adjuvant. Previous attempts to identify an LpxE ortholog in Aquifex aeolicus have failed. A distant lipid A 1‐phosphatase ortholog was identified in Aquifex aeolicus (AaLpxE) and expressed in E. coli . To date, all characterized LpxE orthologues have been unable to dephosphorylate phosphatidylglycerol‐phosphate (PGP), a major intermediate of phospholipid biosynthesis. AaLpxE is unique among LpxE family members in that it functions as both a lipid A 1‐phosphatase and PGP phosphatase in vitro and in vivo . AaLpxE was purified to homogeneity and its dual activities were studied using highly sensitive in vitro assays. The study of AaLpxE provides a model system for the study of substrate specificity of lipid processing enzymes. This research was supported by NIH grant GM51796 to C.R.H. Raetz.