Characterization of solanesyl and decaprenyl diphosphate synthases in mice and humans

Abstract

Ubiquinone (coenzyme Q) functions as an electron transporter in aerobic respiration and oxidative phosphorylation in the respiratory chain [1]. In addition, many reports suggest that ubiquinone also functions as a lipid-soluble antioxidant in cellular biomembranes, scavenging reactive oxygen species [2][3][4][5]. Indeed, several studies using yeast strains that do not produce ubiquinone suggest that an in vitro function of ubiquinone is to protect against oxidants [6,7]. Another phenotype of such ubiquinone-deficient fission yeast is that they generate high levels of hydrogen sulfide [8][9][10]. As Schizosaccharomyces pombe and other eukaryotes are known to carry sulfide-ubiquinone reductase, an enzyme that oxidizes sulfide via ubiquinone [11], it has been suggested that ubiquinone is linked to sulfide metabolism in many organisms. In addition, it was The isoprenoid chain of ubiquinone (Q) is determined by trans-polyprenyl diphosphate synthase in micro-organisms and presumably in mammals. Because mice and humans produce Q 9 and Q 10 , they are expected to possess solanesyl and decaprenyl diphosphate synthases as the determining enzyme for a type of ubiquinone. Here we show that murine and human solanesyl and decaprenyl diphosphate synthases are heterotetramers composed of newly characterized hDPS1 (mSPS1) and hDLP1 (mDLP1), which have been identified as orthologs of Schizosaccharomyces pombe Dps1 and Dlp1, respectively. Whereas hDPS1 or mSPS1 can complement the S. pombe dps1 disruptant, neither hDLP1 nor mDLP1 could complement the S. pombe dLp1 disruptant. Thus, only hDPS1 and mSPS1 are functional orthologs of SpDps1. Escherichia coli was engineered to express murine and human SpDps1 and ⁄ or SpDlp1 homologs and their ubiquinone types were determined. Whereas transformants expressing a single component produced only Q 8 of E. coli origin, double transformants expressing mSPS1 and mDLP1 or hDPS1 and hDLP1 produced Q 9 or Q 10 , respectively, and an in vitro activity of solanesyl or decaprenyl diphosphate synthase was verified. The complex size of the human and murine long-chain transprenyl diphosphate synthases, as estimated by gel-filtration chromatography, indicates that they consist of heterotetramers. Expression in E. coli of heterologous combinations, namely, mSPS1 and hDLP1 or hDPS1 and mDLP1, generated both Q 9 and Q 10 , indicating both components are involved in determining the ubiquinone side chain. Thus, we identified the components of the enzymes that determine the side chain of ubiquinone in mammals and they resembles the S. pombe, but not plant or Saccharomyces cerevisiae, type of enzyme.Abbreviations

A Solanesyl-diphosphate Synthase Localizes in Glycosomes of Trypanosoma cruzi

“…A number of genes encoding polyprenyl-diphosphate synthases from bacteria have been successfully expressed in these E. coli mutants (33,60). The TcSPPS protein is assumed to work as a homodimer, because it is functional without any other genes, unlike the case of Bacillus subtilis heptaprenyl-diphosphate synthase (heterodimer) (61), fission yeast decaprenyl-diphosphate synthase (62), mouse solanesyl-diphosphate synthase (63), and human decaprenyldiphosphate synthase (heterotetramers) (63).…”

“…A, the activity of these proteins has been experimentally demonstrated, although catalytic subunits SpDPS1 and HsDPS1 are not functional alone (62,63). Shaded areas represent amino acids identical to those in TcSPPS.…”

Clinical utility of PDSS2 expression to stratify patients at risk for recurrence of hepatocellular carcinoma

“…In the absence of prenyl diphosphate synthase activity, CoQ10 is not synthesized (15). Therefore, decreased expression of PDSS2 in the liver tissues may lead to reduced synthesis of CoQ10 by hepatocytes, resulting in the inhibition of tumor suppressors (17,18).…”

“…PDSSs are heterotetrameric enzymes comprising subunits encoded by PDSS1 (10p12.1) and PDSS2 (15,16). In the absence of prenyl diphosphate synthase activity, CoQ10 is not synthesized (15).…”

“…Prenyl diphosphate synthase subunit 2 (PDSS2) was identified in 2005 (15), it encodes the second subunit of prenyl diphosphate synthase, which is an essential enzyme involved in the biosynthesis of coenzyme Q10 (CoQ10), and PDSS2 determines the side-chain length of mammalian ubiquinones (16). CoQ10 is synthesized from mevalonic acid in the liver and plays a vital role in the mitochondrial respiratory chain, pyrimidine nucleoside biosynthesis and the modulation of cell apoptosis (17).…”