Escherichia coli YbbF/LpxH and related proteins, metallophosphatase domain
YbbF/LpxH is an Escherichia coli UDP-2,3-diacylglucosamine hydrolase thought to catalyze the fourth step of lipid A biosynthesis, in which a precursor UDP-2,3-diacylglucosamine is hydrolyzed to yield 2,3-diacylglucosamine 1-phosphate and UMP. YbbF belongs to the metallophosphatase (MPP) superfamily. MPPs are functionally diverse, but all share a conserved domain with an active site consisting of two metal ions (usually manganese, iron, or zinc) coordinated with octahedral geometry by a cage of histidine, aspartate, and asparagine residues. The MPP superfamily includes: Mre11/SbcD-like exonucleases, Dbr1-like RNA lariat debranching enzymes, YfcE-like phosphodiesterases, purple acid phosphatases (PAPs), YbbF-like UDP-2,3-diacylglucosamine hydrolases, and acid sphingomyelinases (ASMases). The conserved domain is a double beta-sheet sandwich with a di-metal active site made up of residues located at the C-terminal side of the sheets. This domain is thought to allow for productive metal coordination.