Mechanism and substrate specificity of the flavin reductase ActVB from Streptomyces coelicolor
Mechanism and substrate specificity of the flavin reductase ActVB from Streptomyces coelicolor
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DOI：
10.1074/jbc.m209689200
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发表时间：
2003-01-03
影响因子：
4.8
通讯作者：
Nivière, V
中科院分区：
文献类型：
--
作者：
Filisetti, L;Fontecave, M;Nivière, V
ActVB是天蓝色链霉菌中参与放线菌紫素合成的最后一步的NADH：黄素氧化还原酶。它是一类具有序列和功能相似性的黄素还原酶的原型。研究了ActVB还原游离黄素的机理。虽然ActVB与FMN结合分离，但我们已经证明它不是黄素蛋白。相反，ActVB仅含有一个黄素结合位点，适合黄素还原酶活性并对FMN具有高亲和力。此外，ActVB通过有序的顺序机制进行，其中NADH是第一底物。而ActVB对NADH具有高度特异性，它能够催化多种天然和合成黄素的还原，但K-m值范围为1 μ M（FMN）至69 μ M（荧光黄素）。我们发现，核糖醇磷酸链和异咯嗪环有助于蛋白质-黄素相互作用。这样的性质是独特的，并且将ActVB家族与充分表征的Fre黄素还原酶家族区分开来。
ActVB is the NADH:flavin oxidoreductase participating in the last step of actinorhodin synthesis in Streptomyces coelicolor. It is the prototype of a whole class of flavin reductases with both sequence and functional similarities. The mechanism of reduction of free flavins by ActVB has been studied. Although ActVB was isolated with FMN bound, we have demonstrated that it is not a flavoprotein. Instead, ActVB contains only one flavin binding site, suitable for the flavin reductase activity and with a high affinity for FMN. In addition, ActVB proceeds by an ordered sequential mechanism, where NADH is the first substrate. Whereas ActVB is highly specific for NADH, it is able to catalyze the reduction of a great variety of natural and synthetic flavins, but with K-m values ranging from I muM (FMN) to 69 muM (lumiflavin). We show that both the ribitol-phosphate chain and the isoalloxazine ring contribute to the protein-flavin interaction. Such properties are unique and set the ActVB family apart from the well characterized Fre flavin reductase family.