Fig. 3.

Kdo₂-lipid A modification by KdoO involves hydroxylation and requires O₂ A, B, and C. Cells expressing either YpKdoO or BaKdoO accumulate a Kdo₂-lipid A derivative that is 16 amu larger than Kdo₂-lipid A, consistent with the incorporation of a single oxygen atom and the generation of Ko-Kdo-lipid A (predicted [M-2H]^2- at m/z 1,125.658). D and E. Growth in the absence of oxygen has no effect on the vector control but inhibits KdoO-dependent hydroxylation of Kdo₂-lipid A. Schematic descriptions are the same as in Fig. 1.