Involved in dapdiamide antibiotics biosynthesis. Ligates fumarate and 2,3-diaminopropionate (DAP) to form N-beta-fumaroyl-DAP. Can also form N-succinoyl-DAP from succinate and DAP, with lower efficiency. (S)-2,3-diaminopropanoate + ATP + fumarate = AMP + diphosphate + N(3)-fumaroyl-(S)-2,3-diaminopropanoate kcat is 11.6 sec(-1) with fumarate as substrate. kcat is 3.8 sec(-1) with succinate as substrate. Antibiotic biosynthesis.