Catalyzes the addition of a phosphoethanolamine moiety to the outer membrane lipopolysaccharide core (By similarity). Plays a role in the pathogenesis of E.coli meningitis. Required for invasion of E.coli K1 into brain microvascular endothelial cells (BMEC). Contributes to E.coli traversal across the blood-brain barrier. Bacterial outer membrane biogenesis; LPS core biosynthesis. Belongs to the phosphoethanolamine transferase family. EptC/CptA subfamily.