Aminocarboxypropyltransferase that catalyzes the aminocarboxypropyl transfer on pseudouridine corresponding to position 914 in M.jannaschii 16S rRNA. It constitutes the last step in biosynthesis of the hypermodified N1-methyl-N3-(3-amino-3-carboxypropyl) pseudouridine (m1acp3-Psi)