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Crystal structure of LpxK: The tetraacyldisaccharide 4′‐kinase of lipid A biosynthesis
Author(s) -
Emptage Ryan Paul,
Daughtry Kelly D.,
Pemble Charles W.,
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.791.1
Subject(s) - aquifex aeolicus , transferase , chemistry , hydrolase , nucleoside , stereochemistry , lipid a , biochemistry , linker , protein kinase domain , active site , kinase , enzyme , biology , bacteria , genetics , escherichia coli , mutant , gene , operating system , computer science
The tetraacyldisaccharide 4′‐kinase LpxK catalyzes the sixth step in the biosynthetic pathway of lipid A, the hydrophobic anchor of lipopolysaccharide and an essential membrane component for the vast majority of Gram‐negative bacteria. LpxK is the only known member of the diverse P‐loop containing nucleoside triphosphate hydrolase superfamily to phosphorylate a lipid substrate. Using a single anomalous dispersion dataset collected from selenomethionine‐derivitized protein, the structure of Aquifex aeolicus LpxK was solved in both apo and ADP/Mg 2+ ‐bound forms to a resolution of 1.9 Å and 2.2 Å respectively. LpxK consists of two α/β/α domains connected by a two‐stranded β‐sheet linker which close around ADP/Mg 2+ upon binding. The larger N‐terminal domain is responsible for catalysis at the P‐loop and positioning of the disaccharide‐1‐phosphate substrate for phosphoryl transfer while the smaller C‐terminal domain's primary role is nucleoside binding. The structures along with point mutagenesis studies reveal the importance of highly conserved active site functionalities which are necessary for positioning of the β‐phosphate and catalytic Mg 2+ ion. This work has led to an increased understanding of the 4′‐kinase's enzymatic mechanism and provided the foundation for structure‐based antimicrobial design. This research was funded by N.I.H. grant GM51310 to C.R.H. Raetz.