N,N'-diacetyllegionaminate synthase (, neuB (gene), legI (gene)) is an enzyme with systematic name phosphoenolpyruvate:2,4-diacetamido-2,4,6-trideoxy-alpha-D-mannopyranose 1-(2-carboxy-2-oxoethyl)transferase. This enzyme catalyses the following chemical reaction
This enzyme requires a divalent metal such as Mn<sup>2+</sup>.