Characterization of Sulfolobus solfataricus 2-keto-3-deoxy-D-gluconate kinase in the modified Entner-Doudoroff pathway
Characterization of Sulfolobus solfataricus 2-keto-3-deoxy-D-gluconate kinase in the modified Entner-Doudoroff pathway
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DOI：
10.1271/bbb.50566
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发表时间：
2006-06-01
影响因子：
1.6
通讯作者：
Lee, Sun Bok
中科院分区：
文献类型：
--
作者：
Kim, Seonghun;Lee, Sun Bok
嗜热嗜酸古菌Sulfolobus solfatarieus已知通过非磷酸化Entner-Doudoroff（艾德）途径利用D-葡萄糖。但是，基因组数据库显示该微生物具有编码2-酮-3-脱氧-D-葡萄糖酸（KDG）激酶（KDGK）的基因（kdgK），该激酶将KDG磷酸化为2-酮-3-脱氧-6-磷酸葡萄糖酸。有趣的是，kdgK和其他三个基因在修改艾德途径组织作为一个操纵子样结构。在这项研究中，我们报告确认的催化活性的S。Solfataricus KDGK蛋白。我们还发现，kdgK基因转录为多顺反子转录本。细胞裂解物的蛋白质组学分析显示，所有的基因产物中的kdgK操纵子表达的功能蛋白。这些结果有力地表明S. Solfataricus通过“部分”非磷酸化的艾德途径代谢D-葡萄糖。纯化的重组S. solfataricus KDGK对KDG的Km和k（cat）值分别为0.14 mm和60.8 s（-1），并在70 - 80 ℃温度和7.0 - 8.0 pH值下显示最大活性。
The thermoacidophilic archaeon Sulfolobus solfatarieus is known to utilize D-glucose via the nonphosphorylated Entner-Doudoroff (ED) pathway. But, the genome database shows that this microorganism has a gene (kdgK) encoding 2-keto-3-deoxy-D-gluconate (KDG) kinase (KDGK) which phosphorylates KDG to 2-keto-3-deoxy-6-phosphogluconate. Interestingly, kdgK and three other genes in the modified ED pathway are organized as an operon-like structure. In this study, we report confirmation of the catalytic activity of the S. solfataricus KDGK protein. We also found that the kdgK gene was transcribed as polycistronic transcripts. Proteome analysis of cell lysate revealed that all gene products in the kdgK operon were expressed as functional proteins. These results strongly indicate that S. solfataricus metabolizes D-glucose via the 'partially' nonphosphorylated ED pathway. A purified recombinant S. solfataricus KDGK had K-m and k(cat) values of 0.14 mm and 60.8 s(-1) respectively for KDG, and showed maximal activity at temperatures between 70 and 80 degrees C and pHs between 7.0 and 8.0.