两个NAD连接的氧化还原梭在酿酒酵母中维持过氧化物酶体氧化还原平衡。,Scientific Reports

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两个NAD连接的氧化还原梭在酿酒酵母中维持过氧化物酶体氧化还原平衡。
Scientific Reports ( IF 3.8 ) Pub Date : 2017-Sep-19 , DOI: 10.1038/s41598-017-11942-2
Nadal A. Al-Saryi , Murtakab Y Al-Hejjaj , Carlo W. T. van Roermund , Georgia E. Hulmes , Lakhan Ekal , Chantell Payton , Ronald J. A. Wanders , Ewald H. Hettema

在酿酒酵母中，过氧化物酶体是脂肪酸β-氧化的唯一位点。在此过程中，NAD ⁺还原为NADH。当细胞在油酸盐培养基上生长时，过氧化物酶体NADH被苹果酸脱氢酶（Mdh3p）再氧化成NAD ⁺，还原等同物通过苹果酸/草酰乙酸盐转运蛋白转移到细胞质中。赖氨酸生物合成的最终步骤，即糖精的NAD ⁺依赖性脱氢，是另一个NAD ⁺过氧化物酶体内部进行的依赖反应。我们已经发现，在葡萄糖生长的细胞中，苹果酸/草酰乙酸穿梭和依赖于3-磷酸甘油脱氢酶1（Gpd1p）的穿梭都能够维持过氧化物酶体内部的氧化还原平衡。MDH3或GPD1中的单个突变体在赖氨酸缺乏的培养基上生长，但是mdh3 /gpd1Δ双重突变体积累了saccharopine并显示出赖氨酸缓慢运动。当糖碱脱氢酶错位到mdh3 /gpd1Δ细胞中的胞质溶胶时，赖氨酸的生物合成得以恢复。我们得出结论，过氧化物酶体内NAD ⁺的可用性糖梭脱氢酶活性所需的两个梭子都可以维持。这些穿梭每个对过氧化物酶体内氧化还原平衡的贡献程度取决于生长培养基。我们建议存在多个过氧化物酶体氧化还原穿梭允许真核细胞在不同的代谢条件下维持过氧化物酶体的氧化还原状态。

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Two NAD-linked redox shuttles maintain the peroxisomal redox balance in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, peroxisomes are the sole site of fatty acid β-oxidation. During this process, NAD⁺ is reduced to NADH. When cells are grown on oleate medium, peroxisomal NADH is reoxidised to NAD⁺ by malate dehydrogenase (Mdh3p) and reduction equivalents are transferred to the cytosol by the malate/oxaloacetate shuttle. The ultimate step in lysine biosynthesis, the NAD⁺-dependent dehydrogenation of saccharopine to lysine, is another NAD⁺-dependent reaction performed inside peroxisomes. We have found that in glucose grown cells, both the malate/oxaloacetate shuttle and a glycerol-3-phosphate dehydrogenase 1(Gpd1p)-dependent shuttle are able to maintain the intraperoxisomal redox balance. Single mutants in MDH3 or GPD1 grow on lysine-deficient medium, but an mdh3/gpd1Δ double mutant accumulates saccharopine and displays lysine bradytrophy. Lysine biosynthesis is restored when saccharopine dehydrogenase is mislocalised to the cytosol in mdh3/gpd1Δ cells. We conclude that the availability of intraperoxisomal NAD⁺ required for saccharopine dehydrogenase activity can be sustained by both shuttles. The extent to which each of these shuttles contributes to the intraperoxisomal redox balance may depend on the growth medium. We propose that the presence of multiple peroxisomal redox shuttles allows eukaryotic cells to maintain the peroxisomal redox status under different metabolic conditions.

更新日期：2017-09-19

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