The B Form of Dihydroorotate Dehydrogenase from Lactococcus lactis Consists of Two Different Subunits, Encoded by the pyrDb and pyrK Genes, and Contains FMN, FAD, and [FeS] Redox Centers*
The B Form of Dihydroorotate Dehydrogenase from Lactococcus lactis Consists of Two Different Subunits, Encoded by the pyrDb and pyrK Genes, and Contains FMN, FAD, and [FeS] Redox Centers*
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来自乳酸乳球菌的 B 型二氢乳清酸脱氢酶由两个不同的亚基组成，由pyrDb 和pyrK 基因编码，并包含FMN、FAD 和[FeS] 氧化还原中心*
DOI：
10.1074/jbc.271.46.29359
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
K. Jensen
中科院分区：
文献类型：
--
作者：
F. Nielsen;P. Andersen;K. Jensen
The B form of dihydroorotate dehydrogenase from Lactococcus lactis (DHOdehase B) is encoded by the pyrDb gene. However, recent genetic evidence has revealed that a co-transcribed gene, pyrK, is needed to achieve the proper physiological function of the enzyme. We have purified DHOdehase B from two strains of Escherichia coli, which harbored either the pyrDb gene or both the pyrDb and the pyrK genes of L. lactis on multicopy plasmids. The enzyme encoded by pyrDb alone (herein called the δ-enzyme) was a bright yellow, dimeric protein that contained one molecule of tightly bound FMN per subunit. The δ-enzyme exhibited dihydroorotate dehydrogenase activity with dichloroindophenol, potassium hexacyanoferrate(III), and molecular oxygen as electron acceptors but could not use NAD+. The DHOdehase B purified from the E. coli strain that carried both the pyrDb and pyrK genes on a multicopy plasmid (herein called the δκ-enzyme) was quite different, since it was formed as a complex of equal amounts of the two polypeptides, i.e. two PyrDB and two PyrK subunits. The δκ-enzyme was orange-brown and contained 2 mol of FAD, 2 mol of FMN, and 2 mol of [2Fe-2S] redox clusters per mol of native protein as tightly bound prosthetic groups. The δκ-enzyme was able to use NAD+ as well as dichloroindophenol, potassium hexacyanoferrate(III), and to some extent molecular oxygen as electron acceptors for the conversion of dihydroorotate to orotate, and it was a considerably more efficient catalyst than the purified δ-enzyme. Based on these results and on analysis of published sequences, we propose that the architecture of the δκ-enzyme is representative for the dihydroorotate dehydrogenases from Gram-positive bacteria.
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影响因子：
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期刊：
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影响因子：
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