Involved in the biosynthesis of lipid A, a phosphorylated glycolipid that anchors the lipopolysaccharide to the outer membrane of the cell. a (3R)-hydroxyacyl-[ACP] + UDP-N-acetyl-alpha-D-glucosamine = a UDP-3-O-[(3R)-3-hydroxyacyl]-N-acetyl-alpha-D-glucosamine + holo-[ACP] Glycolipid biosynthesis; lipid IV(A) biosynthesis; lipid IV(A) from (3R)-3-hydroxytetradecanoyl-[acyl-carrier-protein] and UDP-N-acetyl-alpha-D-glucosamine: step 1/6. Homotrimer. Belongs to the transferase hexapeptide repeat family. LpxA subfamily.