Fig. 6.

Purified LpxT transfers a phosphate group from C₅₅-PP to lipid A. A. Purified LpxT was assayed for phosphatase activity in the presence of [¹⁴C]C₅₅-PP as described in the text. Following separation by TLC, the lipids were located and quantified with a radioactivity scanner. B. Purified LpxT was assayed for 1-phosphotransferase activity using Kdo₂-[4′-³²P]lipid A. The protein concentration was 0.001 mg ml⁻¹ and assays were carried out for 3 h at 30°C with 5 μM Kdo₂-[4′-³²P]lipid A and 100 μM of C₅₅-P or C₅₅-PP as the substrates. The products were separated by TLC and detected with PhosphorImager analysis.