Department of Chemistry and Biochemistry, Gonzaga University, Spokane, WA 99258-0005, USA.
J Bacteriol. 2010 Jan;192(2):436-45. doi: 10.1128/JB.01040-09. Epub 2009 Nov 20.
Rhodoquinone (RQ) is an important cofactor used in the anaerobic energy metabolism of Rhodospirillum rubrum. RQ is structurally similar to ubiquinone (coenzyme Q or Q), a polyprenylated benzoquinone used in the aerobic respiratory chain. RQ is also found in several eukaryotic species that utilize a fumarate reductase pathway for anaerobic respiration, an important example being the parasitic helminths. RQ is not found in humans or other mammals, and therefore inhibition of its biosynthesis may provide a parasite-specific drug target. In this report, we describe several in vivo feeding experiments with R. rubrum used for the identification of RQ biosynthetic intermediates. Cultures of R. rubrum were grown in the presence of synthetic analogs of ubiquinone and the known Q biosynthetic precursors demethylubiquinone, demethoxyubiquinone, and demethyldemethoxyubiquinone, and assays were monitored for the formation of RQ(3). Data from time course experiments and S-adenosyl-l-methionine-dependent O-methyltransferase inhibition studies are discussed. Based on the results presented, we have demonstrated that Q is a required intermediate for the biosynthesis of RQ in R. rubrum.
红紫质醌（RQ）是用于红螺菌厌氧能量代谢的重要辅助因子。RQ 在结构上与泛醌（辅酶 Q 或 Q）相似，泛醌是用于需氧呼吸链的聚异戊二烯化苯醌。RQ 也存在于几种利用延胡索酸还原酶途径进行厌氧呼吸的真核生物中，寄生虫是一个重要的例子。RQ 不存在于人类或其他哺乳动物中，因此抑制其生物合成可能为寄生虫提供特异性的药物靶点。在本报告中，我们描述了使用红螺菌进行的几种体内喂养实验，用于鉴定 RQ 生物合成中间体。在存在合成泛醌类似物以及已知的 Q 生物合成前体脱甲基泛醌、脱甲氧基泛醌和脱甲基脱甲氧基泛醌的情况下培养红螺菌，并监测 RQ(3)的形成。讨论了时程实验和 S-腺苷甲硫氨酸依赖性 O-甲基转移酶抑制研究的数据。根据呈现的结果，我们已经证明 Q 是红螺菌中 RQ 生物合成所必需的中间产物。
