Nishida Ikuhisa, Yanai Ryota, Matsuo Yasuhiro, Kaino Tomohiro, Kawamukai Makoto
Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, Japan.
Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan.
PLoS One. 2020 Nov 24;15(11):e0242616. doi: 10.1371/journal.pone.0242616. eCollection 2020.
Coenzyme Q (CoQ, ubiquinone) is an essential component of the electron transport system in aerobic organisms. Human type CoQ10, which has 10 units of isoprene in its quinone structure, is especially valuable as a food supplement. Therefore, studying the biosynthesis of CoQ10 is important not only for increasing metabolic knowledge, but also for improving biotechnological production. Herein, we show that Schizosaccharomyces pombe utilizes p-aminobenzoate (PABA) in addition to p-hydroxybenzoate (PHB) as a precursor for CoQ10 synthesis. We explored compounds that affect the synthesis of CoQ10 and found benzoic acid (Bz) at >5 μg/mL inhibited CoQ biosynthesis without accumulation of apparent CoQ intermediates. This inhibition was counteracted by incubation with a 10-fold lower amount of PABA or PHB. Overexpression of PHB-polyprenyl transferase encoded by ppt1 (coq2) also overcame the inhibition of CoQ biosynthesis by Bz. Inhibition by Bz was efficient in S. pombe and Schizosaccharomyces japonicus, but less so in Saccharomyces cerevisiae, Aureobasidium pullulans, and Escherichia coli. Bz also inhibited a S. pombe ppt1 (coq2) deletion strain expressing human COQ2, and this strain also utilized PABA as a precursor of CoQ10. Thus, Bz is likely to inhibit prenylation reactions involving PHB or PABA catalyzed by Coq2.
辅酶Q（CoQ，泛醌）是需氧生物电子传递系统的重要组成部分。人类的辅酶Q10在其醌结构中有10个异戊二烯单元，作为食品补充剂特别有价值。因此，研究辅酶Q10的生物合成不仅对于增加代谢知识很重要，而且对于改进生物技术生产也很重要。在此，我们表明粟酒裂殖酵母除了利用对羟基苯甲酸（PHB）外，还利用对氨基苯甲酸（PABA）作为辅酶Q10合成的前体。我们探索了影响辅酶Q10合成的化合物，发现浓度>5μg/mL的苯甲酸（Bz）会抑制辅酶Q的生物合成，且不会积累明显的辅酶Q中间体。通过与低10倍量的PABA或PHB孵育可抵消这种抑制作用。由ppt1（coq2）编码的PHB - 聚异戊二烯转移酶的过表达也克服了Bz对辅酶Q生物合成的抑制。Bz的抑制作用在粟酒裂殖酵母和日本裂殖酵母中有效，但在酿酒酵母、出芽短梗霉和大肠杆菌中效果较差。Bz还抑制了表达人COQ2的粟酒裂殖酵母ppt1（coq2）缺失菌株，并且该菌株也利用PABA作为辅酶Q10的前体。因此，Bz可能抑制由Coq2催化的涉及PHB或PABA的异戊二烯化反应。
