Catalyzes a mechanistically unusual reaction, the ATP-dependent insertion of CO2 between the N7 and N8 nitrogen atoms of 7,8-diaminopelargonic acid (DAPA, also called 7,8-diammoniononanoate) to form a ureido ring (PubMed:20565114). Can use a range of NTPs; has highest affinity for CTP (KD is measured as 17.2 uM or 0.160 uM in 2 different papers) while KD for ATP is 331 uM or 75 uM in the same papers. Gly-169 plays a role in NTP discrimination (PubMed:25801336, Ref.5). (7R,8S)-7,8-diammoniononanoate + ATP + CO2 = (4R,5S)-dethiobiotin + ADP + 3 H(+) + phosphate Binds 1 Mg(2+) per subunit. Inhibited by ADP. Cofactor biosynthesis; biotin biosynthesis; biotin from 7,8-diaminononanoate: step 1/2. Homodimer. While ADP, ATP, ITP, TTP and UTP can be crystallized in the enzyme in approximately the same place as CTP, it is their phosphate tails that anchor them to the enzyme, their nucleoside moieties do not bind in the same way CTP does. Belongs to the dethiobiotin synthetase family.