Ferulic Acid Decarboxylase Controls Oxidative Maturation of the Prenylated Flavin Mononucleotide Cofactor
Ferulic Acid Decarboxylase Controls Oxidative Maturation of the Prenylated Flavin Mononucleotide Cofactor
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DOI：
10.1021/acschembio.0c00456
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发表时间：
2020-09-18
影响因子：
4
通讯作者：
Leys, David
中科院分区：
文献类型：
--
作者：
Balaikaite, Arune;Chisanga, Malama;Leys, David
异戊烯化黄素单肽（prFMN）是最近发现的含有连接到N5和C6原子的额外非芳香环的修饰的黄素辅因子。该辅因子支持由广泛存在的UbiD酶家族的成员催化的可逆脱羧，并由黄素异戊烯基转移酶UbiX产生。UbiX产物prFMNH（2）氧化成熟为相应的氧化prFMN（亚胺）是阿魏酸脱羧酶（Fdc 1; UbiD型酶）活性所需的。然而，目前还不清楚Fdc 1酶在这一过程中发挥了什么作用。在这里，我们证明，在没有Fdc 1，prFMNH（2）氧化O-2的收益通过一个短暂的半醌prFMN（自由基）的物种，并最终在一个非常稳定的prFMN-过氧化氢物种。两种形式的prFMN都不能支持Fdc 1活性。相反，使用O-2介导的氧化的酶活化需要在氧暴露之前结合prFMNH（2），证实UbiD酶在O-2介导的氧化成熟中起作用。与此形成鲜明对比的是，替代氧化剂，如铁氰化钾支持prFMN（亚胺）的形成，在溶液中，并在Fdc 1。
Prenylated flavin mononucleotide (prFMN) is a recently discovered modified flavin cofactor containing an additional nonaromatic ring, connected to the N5 and C6 atoms. This cofactor underpins reversible decarboxylation catalyzed by members of the widespread UbiD enzyme family and is produced by the flavin prenyltransferase UbiX. Oxidative maturation of the UbiX product prFMNH(2) to the corresponding oxidized prFMN(iminium) is required for ferulic acid decarboxylase (Fdc1; a UbiD-type enzyme) activity. However, it is unclear what role the Fdc1 enzyme plays in this process. Here, we demonstrate that, in the absence of Fdc1, prFMNH(2) oxidation by O-2 proceeds via a transient semiquinone prFMN(radical) species and culminates in a remarkably stable prFMN-hydroperoxide species. Neither forms of prFMN are able to support Fdc1 activity. Instead, enzyme activation using O-2-mediated oxidation requires prFMNH(2) binding prior to oxygen exposure, confirming that UbiD enzymes play a role in O-2-mediated oxidative maturation. In marked contrast, alternative oxidants such as potassium ferricyanide support prFMN(iminium) formation both in solution and in Fdc1.