Functional conservation of coenzyme Q biosynthetic genes among yeasts, plants, and humans.

Kazuhiro Hayashi,Makoto Kawamukai,Yuki Ogiyama,Kazumasa Yokomi,Tsuyoshi Nakagawa,Tomohiro Kaino,Takashi Toda

doi:10.1371/journal.pone.0099038

Abstract

Coenzyme Q (CoQ) is an essential factor for aerobic growth and oxidative phosphorylation in the electron transport system. The biosynthetic pathway for CoQ has been proposed mainly from biochemical and genetic analyses of Escherichia coli and Saccharomyces cerevisiae; however, the biosynthetic pathway in higher eukaryotes has been explored in only a limited number of studies. We previously reported the roles of several genes involved in CoQ synthesis in the fission yeast Schizosaccharomyces pombe. Here, we expand these findings by identifying ten genes (dps1, dlp1, ppt1, and coq3–9) that are required for CoQ synthesis. CoQ10-deficient S. pombe coq deletion strains were generated and characterized. All mutant fission yeast strains were sensitive to oxidative stress, produced a large amount of sulfide, required an antioxidant to grow on minimal medium, and did not survive at the stationary phase. To compare the biosynthetic pathway of CoQ in fission yeast with that in higher eukaryotes, the ability of CoQ biosynthetic genes from humans and plants (Arabidopsis thaliana) to functionally complement the S. pombe coq deletion strains was determined. With the exception of COQ9, expression of all other human and plant COQ genes recovered CoQ10 production by the fission yeast coq deletion strains, although the addition of a mitochondrial targeting sequence was required for human COQ3 and COQ7, as well as A. thaliana COQ6. In summary, this study describes the functional conservation of CoQ biosynthetic genes between yeasts, humans, and plants.

Highlights

Coenzyme Q (CoQ), known as ubiquinone, is an isoprenoid quinone that is distributed widely in almost all living organisms [1,2,3]
We examined the involvement of ten S. pombe coq genes (Figure 1 and Table 2) in CoQ biosynthesis
We constructed four new S. pombe deletion strains in which the coq4 (SPAC1687.12c), coq5 (SPCC4G3.04c), coq6 (SPBC146.12), or coq9 (SPAC19G12.11) gene was replaced with the kanr marker (Figure S1 and Table 1)

Summary

Introduction

Coenzyme Q (CoQ), known as ubiquinone, is an isoprenoid quinone that is distributed widely in almost all living organisms [1,2,3]. In S. cerevisiae, the biosynthetic pathway that converts PHB to CoQ comprises at least eight steps that require at least seven enzymes with assigned roles [1,2,17]; these steps include the condensation and transfer of the isoprenoid side chain to PHB, followed by methylations, decarboxylation and hydroxylations (Figure 1). PHBpolyprenyl diphosphate transferase, known as Coq in budding yeast [19] or Ppt in fission yeast [20], catalyzes the condensation of PHB (or pABA) with the isoprenoid chain. Coq (Omethyltransferase) catalyzes the two O-methylation steps in the CoQ biosynthetic pathway [21,22]. Coq is absolutely required for CoQ biosynthesis but its enzymatic function remains unknown [23]. Coq is required for CoQ biosynthesis but its enzymatic function is unknown [29]. Coq is a binding protein of CoQ [30,31], and indirectly affects but is not required for CoQ synthesis [32]

Methods

Results

Conclusion