Crystal structures of Mycobacteria tuberculosis and Klebsiella pneumoniae UDP-galactopyranose mutase in the oxidised state and Klebsiella pneumoniae UDP-galactopyranose mutase in the (active) reduced state.
Crystal structures of Mycobacteria tuberculosis and Klebsiella pneumoniae UDP-galactopyranose mutase in the oxidised state and Klebsiella pneumoniae UDP-galactopyranose mutase in the (active) reduced state.
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DOI：
10.1016/j.jmb.2005.02.057
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发表时间：
2005-05-13
影响因子：
5.6
通讯作者：
Naismith, JH
中科院分区：
文献类型：
--
作者：
Beis, K;Srikannathasan, V;Liu, H;Fullerton, SWB;Bamford, VA;Sanders, DAR;Whitfield, C;McNeil, MR;Naismith, JH
尿苷二磷酸半乳糖呋喃糖（UDP-Galf）是在细菌和寄生细胞壁中发现的d -半乳糖呋喃糖的前体，包括许多病原体。udp -半乳糖是由udp -半乳糖氨基糖通过udp -半乳糖氨基糖变化酶合成的。酶的活性需要还原的FADH -辅因子。具有FAD的结核分枝杆菌突变酶的结构已确定为2.25Å。用FAD和FADH -结合的肺炎克雷伯菌突变酶的结构分别测定了2.2Å和2.35Å的分辨率。这是首次报道含有FADH的结构。已经提出了两种依赖黄素的酶的机制，一种涉及在黄素上形成共价加合物，另一种基于电子转移。利用我们的结构数据，我们研究了这两种机制。电子传递机制与结构数据是一致的，这并不奇怪，因为它对原子的精确定位要求较少。基于共价加合物FAD的模型需要酶活性位点的重新定位，并且似乎需要FADH -的异alloxazine环以特定的方式弯曲。然而，FADH -结构揭示了异allox嗪环以相反的方式弯曲，这显然需要共价加合物来触发蛋白质的深刻构象变化或弯曲与载脂蛋白结构相反的FADH -。
Uridine diphosphogalactofuranose (UDP-Galf) is the precursor of the D-galactofuranose sugar found in bacterial and parasitic cell walls, including those of many pathogens. UDP-Galf is made from UDP-galactopyranose by the enzyme UDP-galactopyranose mutase. The enzyme requires the reduced FADH− co-factor for activity. The structure of the Mycobacterium tuberculosis mutase with FAD has been determined to 2.25Å. The structures of Klebsiella pneumoniae mutase with FAD and with FADH− bound have been determined to 2.2Å and 2.35Å resolutions respectively. This is the first report of the FADH− containing structure. Two flavin dependent mechanisms for the enzyme have been proposed, one which involves a covalent adduct being formed at the flavin and the other based on electron transfer. Using our structural data, we have examined the two mechanisms. The electron transfer mechanism is consistent with the structural data, not surprisingly since it makes fewer demands on the precise positioning of atoms. A model based on a covalent adduct FAD requires repositioning of the enzyme active site and would appear to require that the isoalloxazine ring of FADH− to buckle in a particular way. However, the FADH− structure reveals that the isoalloxazine ring buckles in the opposite sense, this apparently requires the covalent adduct to trigger profound conformational changes in the protein or to buckle the FADH− opposite to that seen in the apo structure.
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影响因子：
4.8
作者：
Haynes, CA;Koder, RL;Rodgers, DW
通讯作者：
Rodgers, DW
影响因子：
4.8
作者：
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3.5
作者：
BURLEY, SK;PETSKO, GA
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PETSKO, GA
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Fullerton, SWB;Daff, S;Naismith, JH
通讯作者：
Naismith, JH
影响因子：
3.2
作者：
Pan, F;Jackson, M;McNeil, M
通讯作者：
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