A subunit of decaprenyl diphosphate synthase stabilizes octaprenyl diphosphate synthase in Escherichia coli by forming a high-molecular weight complex

AbstractThe length of the isoprenoid-side chain in ubiquinone, an essential component of the electron transport chain, is defined by poly-prenyl diphosphate synthase, which comprises either homomers (e.g., IspB in Escherichia coli) or heteromers (e.g., decaprenyl diphosphate synthase (Dps1) and D-less polyprenyl diphosphate synthase (Dlp1) in Schizosaccharomyces pombe and in humans). We found that expression of either dlp1 or dps1 recovered the thermo-sensitive growth of an E. coli ispBR321A mutant and restored IspB activity and production of Coenzyme Q-8. IspB interacted with Dlp1 (or Dps1), forming a high-molecular weight complex that stabilized IspB, leading to full functionality.Structured summary:MINT-7385426:Dlp1 (uniprotkb:Q86YH6) and IspB (uniprotkb:P0AD57) physically interact (MI:0915) by blue native page (MI:0276)MINT-7385083, MINT-7385058:IspB (uniprotkb:P0AD57) and IspB (uniprotkb:P0AD57) bind (MI:0407) by blue native page (MI:0276)MINT-7385413:Dlp1 (uniprotkb:O13851) and IspB (uniprotkb:P0AD57) physically interact (MI:0915) by blue native page (MI:0276)MINT-7385024:IspB (uniprotkb:P0AD57) physically interacts (MI:0915) with Dps1 (uniprotkb:O43091) by pull down (MI:0096)MINT-7385041:IspB (uniprotkb:P0AD57) physically interacts (MI:0915) with Dlp1 (uniprotkb:O13851) by pull down (MI:0096)MINT-7385388:IspB (uniprotkb:P0AD57) and Dps1 (uniprotkb:O43091) physically interact (MI:0915) by blue native page (MI:0276

<i>Schizosaccharomyces japonicus</i> has low levels of CoQ₁₀ synthesis, respiration deficiency, and efficient ethanol production

<p>Coenzyme Q (CoQ) is essential for mitochondrial respiration and as a cofactor for sulfide quinone reductase. <i>Schizosaccharomyces pombe</i> produces a human-type CoQ₁₀. Here, we analyzed CoQ in other fission yeast species. <i>S. cryophilus</i> and <i>S. octosporus</i> produce CoQ₉. <i>S. japonicus</i> produces low levels of CoQ₁₀, although all necessary genes for CoQ synthesis have been identified in its genome. We expressed three genes (<i>dps1</i>, <i>dlp1</i>, and <i>ppt1</i>) for CoQ synthesis from <i>S. japonicus</i> in the corresponding <i>S. pombe</i> mutants, and confirmed that they were functional. <i>S. japonicus</i> had very low levels of oxygen consumption and was essentially respiration defective, probably due to mitochondrial dysfunction. <i>S. japonicus</i> grows well on minimal medium during anaerobic culture, indicating that it acquires sufficient energy by fermentation. <i>S. japonicus</i> produces comparable levels of ethanol under both normal and elevated temperature (42 °C) conditions, at which <i>S. pombe</i> is not able to grow.</p> <p><i>Schizosaccharomyces japonicus</i> and <i>Schizosaccharomyces pome</i> are distinct in mitochondrial-related functions.</p

Complementation of the <i>S. pombe Δcoq7</i>, <i>Δcoq5,</i> and <i>Δcoq8</i> strains by Hs<i>COQ7,</i> Hs<i>COQ5</i> and Hs<i>COQ8</i>.

<p>(A) HPLC analyses of lipid extracts from the KH7 (<i>Δcoq7</i>) strain expressing <i>S. pombe coq7</i>, Hs<i>COQ7</i>, or Hs<i>COQ7</i> containing a mitochondrial targeting sequence (Mt-signal). The flow speed was doubled to separate the two peaks clearly. DMQ10, demethoxyubiquinone. (B) HPLC analyses of lipid extracts from the KH5 (<i>Δcoq5</i>) strain expressing <i>S. pombe coq5</i> or Hs<i>COQ5</i>. CoQ10 was mixed with the lipid extracts from the KH5 (<i>Δcoq5</i>) strain expressing Hs<i>COQ5</i>. Asterisks indicate the intermediate like peaks found in a <i>coq5</i> deletion strain. (C) HPLC analyses of lipid extracts from the KH8 (<i>Δcoq8</i>) strain expressing <i>S. pombe coq8</i> or Hs<i>COQ8</i>. (D) Cell growth of the indicated strains over 72 h. W.T., wild type strain.</p

Genes involved in CoQ synthesis in <i>S. cerevisiae, S. pombe</i>, humans, and <i>A. thaliana</i>.

<p>Genes involved in CoQ synthesis in <i>S. cerevisiae, S. pombe</i>, humans, and <i>A. thaliana</i>.</p

The proposed CoQ biosynthesis pathway in <i>S. cerevisiae</i>, <i>S. pombe</i>, humans, and <i>A. thaliana</i>.

<p>At least ten genes, three of which have unassigned roles, are responsible for CoQ biosynthesis in <i>S. pombe</i>. All of these <i>S. pombe</i> enzymes have human counterparts, but <i>A. thaliana</i> lacks Coq7 and a component of the prenyl diphosphate synthase in this plant species differs from that in <i>S. pombe</i> and humans. The functions of Coq4 and Coq9 are currently unknown. Coq8 is a protein kinase that regulates the stability of Coq proteins in <i>S. cerevisiae</i>. The involvement of pABA in the CoQ pathway in <i>S. pombe</i>, human and <i>A. thaliana</i> has not yet been established. For simplicity, <i>ARH1</i> and <i>YAH1</i>, which are involved in CoQ synthesis through the regulation of Coq6 in <i>S. cerevisiae</i>, are not shown.</p