The thuEFGKAB Operon of Rhizobia and Agrobacterium tumefaciens Codes for Transport of Trehalose, Maltitol, and Isomers of Sucrose and Their Assimilation through the Formation of Their 3-Keto Derivatives
The thuEFGKAB Operon of Rhizobia and Agrobacterium tumefaciens Codes for Transport of Trehalose, Maltitol, and Isomers of Sucrose and Their Assimilation through the Formation of Their 3-Keto Derivatives
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DOI：
10.1128/jb.00478-13
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发表时间：
2013-09-01
影响因子：
3.2
通讯作者：
Bhuvaneswari, T. V.
中科院分区：
文献类型：
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作者：
Ampomah, Osei Yaw;Avetisyan, Anna;Bhuvaneswari, T. V.
苜蓿中华根瘤菌的清华操纵子编码海藻糖二糖的运输和利用功能。对根瘤科成员的基因组测序表明，一些根瘤菌和农杆菌在相似的组织中拥有整个清华操纵子，而洛伊中根瘤菌MAFF303099缺乏转运蛋白(TUEFGK)基因。在这项研究中，我们发现这个操纵子不仅在苜蓿链霉菌中，而且在根癌农杆菌中，除了海藻糖外，还致力于麦芽糖醇和蔗糖的异构体(白砂糖、棕榈糖和海藻糖)的运输和同化。利用遗传互补的方法，我们证明了紫花苜蓿、紫花苜蓿和根癌农杆菌的TUAB基因在功能上是等价的。此外，我们提供了遗传和生化证据来表明这些细菌通过将它们转化为各自的3-酮基衍生物来同化这些双糖，并且TUAB基因编码这种酮二糖形成酶(S)。拉曼光谱显示了3-酮基海藻糖在活体中的实时形成。还指出在根癌农杆菌中还存在一个额外的酮二糖形成途径(S)。据我们所知，这是在任何生物体中首次发现编码将双糖转化为3-酮二糖衍生物的基因。
The thu operon (thuEFGKAB) in Sinorhizobium meliloti codes for transport and utilization functions of the disaccharide trehalose. Sequenced genomes of members of the Rhizobiaceae reveal that some rhizobia and Agrobacterium possess the entire thu operon in similar organizations and that Mesorhizobium loti MAFF303099 lacks the transport (thuEFGK) genes. In this study, we show that this operon is dedicated to the transport and assimilation of maltitol and isomers of sucrose (leucrose, palatinose, and trehalulose) in addition to trehalulose, not only in S. meliloti but also in Agrobacterium tumefaciens. By using genetic complementation, we show that the thuAB genes of S. meliloti, M. loti, and A. tumefaciens are functionally equivalent. Further, we provide both genetic and biochemical evidence to show that these bacteria assimilate these disaccharides by converting them to their respective 3-keto derivatives and that the thuAB genes code for this ketodisaccharide-forming enzyme(s). Formation of 3-ketotrehalose in real time in live S. meliloti is shown through Raman spectroscopy. The presence of an additional ketodisaccharide-forming pathway(s) in A. tumefaciens is also indicated. To our knowledge, this is the first report to identify the genes that code for the conversion of disaccharides to their 3-ketodisaccharide derivatives in any organism.