6k37
Crystal structure of BioU (K124A) from Synechocystis sp.PCC6803 in complex with NAD+ and the analog of reaction intermediate, 3-(1-aminoethyl)-nonanedioic acid
Structural highlights
FunctionBIOU_SYNY3 A 'suicide' enzyme that participates in biotin synthesis. Catalyzes the formation of (S)-8-amino-7-oxononanoate (DAN-carbamic acid) from (7R,8S)-8-amino-7-(carboxyamino)nonanoate (DAN), a function equivalent to the cannonical BioA reaction and the first half-reaction of BioD. The cellular requirement for biotin is thought be low enough that this single turnover enzyme supplies a sufficient amount of the cofactor. Overall it catalyzes three reactions: formation of a covalent linkage with 8-amino-7-oxononanoate to yield a BioU-DAN conjugate at the epsilon-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)+ (By similarity) (PubMed:32042199). A coupled Synechocystis BioU/BioD assay produces dethiobiotin from DAN. Complements a bioA deletion in E.coli but not a bioD1 deletion (PubMed:32042199).[HAMAP-Rule:MF_00852][1] Publication Abstract from PubMedIn 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 epsilon-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. A suicide enzyme catalyzes multiple reactions for biotin biosynthesis in cyanobacteria.,Sakaki K, Ohishi K, Shimizu T, Kobayashi I, Mori N, Matsuda K, Tomita T, Watanabe H, Tanaka K, Kuzuyama T, Nishiyama M Nat Chem Biol. 2020 Feb 10. pii: 10.1038/s41589-019-0461-9. doi:, 10.1038/s41589-019-0461-9. PMID:32042199[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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