Ma Zheng, Rady Emily W, de Silva Aravinda J, Bellizzi John J
Department of Chemistry and Biochemistry, College of Natural Sciences and Mathematics, The University of Toledo, 2801 W. Bancroft St, Toledo, OH, 43606, U.S.A.
bioRxiv. 2025 Aug 12:2025.08.09.669344. doi: 10.1101/2025.08.09.669344.
BorF is a short-chain flavin reductase from a desert soil bacterium that uses NADH to reduce FAD to FADH, which is used by the tryptophan-6-halogenase BorH to chlorinate tryptophan in the biosynthetic pathway of borregomycin A. The X-ray crystal structure of BorF bound to FAD was solved to 2.37 Å by molecular replacement and consists of a homodimer of single-domain protomers with a Greek key split β-barrel topology containing a domain-swapped N-terminal α-helix, as seen in other members of this family. Insertions and deletions in the region between α3 and β5 lead to a variety of different conformations of the adenosine portion of FAD bound to BorF and structurally related reductases. Comparison of the FAD-bound structures of BorF and BorH suggests that FAD must completely dissociate from BorH in order to be reduced by BorF.
BorF是一种来自沙漠土壤细菌的短链黄素还原酶，它利用NADH将FAD还原为FADH，FADH被色氨酸-6-卤化酶BorH用于在博来霉素A的生物合成途径中氯化色氨酸。通过分子置换法将与FAD结合的BorF的X射线晶体结构解析到2.37 Å，它由单结构域原体的同型二聚体组成，具有希腊钥匙型分裂β桶拓扑结构，包含一个结构域交换的N端α螺旋，这与该家族的其他成员相同。α3和β5之间区域的插入和缺失导致与BorF和结构相关还原酶结合的FAD的腺苷部分有多种不同构象。BorF和BorH的FAD结合结构比较表明，FAD必须从BorH完全解离才能被BorF还原。
