In biotin biosynthesis, the conversion of pimeloyl intermediates to biotin is catalyzed by a universal set of four enzymes: BioF, BioA, BioD and BioB. We found that the gene homologous to bioA, the product of which is involved in the conversion of 8-amino-7-oxononanoate (AON) to 7,8-diaminononanoate (DAN), is missing in the genome of the cyanobacterium Synechocystis sp. PCC 6803. We provide structural and biochemical evidence showing that a novel dehydrogenase, BioU, is involved in biotin biosynthesis and functionally replaces BioA. This enzyme catalyzes three reactions: formation of covalent linkage with AON to yield a BioU-DAN conjugate at the ε-amino group of Lys124 of BioU using NAD(P)H, carboxylation of the conjugate to form BioU-DAN-carbamic acid, and release of DAN-carbamic acid using NAD(P)⁺. In this biosynthetic pathway, BioU is a suicide enzyme that loses the Lys124 amino group after a single round of reaction.

在生物素生物合成中，庚二酰中间体向生物素的转化由一组通用的四种酶催化：BioF、BioA、BioD 和 BioB。我们发现与bioA同源的基因在蓝藻集胞藻的基因组中缺失，该基因的产物涉及 8-氨基-7-氧壬酸 (AON) 到 7,8-二氨基壬酸 (DAN) 的转化。sp。PCC 6803. 我们提供的结构和生化证据表明，一种新型脱氢酶 BioU 参与了生物素的生物合成并在功能上取代了 BioA。该酶催化三个反应：与 AON 形成共价键，使用 NAD(P)H 在​​ BioU 的 Lys124 的 ε-氨基处产生 BioU-DAN 偶联物，偶联物羧化形成 BioU-DAN-氨基甲酸，和使用 NAD(P) ⁺释放 DAN-氨基甲酸。在这种生物合成途径中，BioU 是一种自杀酶，在单轮反应后会失去 Lys124 氨基。