| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Long-chain producing polyprenyl diphosphate synthase, which is responsible for the side chain of ubiquinone, has been mostly analyzed from prokaryotic origins, and little is known about the nature of eukaryotic enzyme. Here, we show decaprenyl diphosphate synthase from Schizosaccharomyces pombe forms a heterotetramer unlike prokaryotic types of enzymes. We found the novel protein named D1pl is the partner of Dps1, and formed a heterotetrameric complex to constitute an active decaprenyl diphosphate synthase in S. pombe. While Dps1 is the highly homologous protein with other prenyl diphosphate synthases, Dlp1 only retains weak homology with Dps1. The deletion mutant of dlp1 lost the enzymatic activity of decaprenyl diphosphate synthase, did not produce UQ-10 and resulted in a typical ubiquinone less phenotype in S. pombe, i.e., hypersensitivity to H_2O_2, requirement of antioxidant to grow on the minimal medium, and an elevated production of H_2S. Both dps1 and dlp1 mutants can be restored by expressing bacterial driven decaprenyl diphosphate synthase which is solely functional, indicating both dps1 and dlp1 is required for the enzymatic activity. Furthermore, we show Dps1 and Dlp1 formed a heterotetrameric complex and reconstituted in an active enzyme in Escherichia coli. Thus, decaprenyl diphosphate from an eukaryotic origin constitutes a heterotetrameric type of enzyme structure which was not found in prokaryotes.
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