NADPH Is an Allosteric Regulator of HSCARG
NADPH Is an Allosteric Regulator of HSCARG
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NADPH 是 HSCARG 的变构调节剂
DOI：
10.1016/j.jmb.2009.02.049
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发表时间：
2009-04-17
影响因子：
5.6
通讯作者：
Zheng, Xiaofeng
中科院分区：
文献类型：
--
作者：
Dai, Xueyu;Li, Yiyu;Zheng, Xiaofeng
NADP（H）是一种重要的辅因子，控制许多基本的细胞过程。我们已经确定了HSCARG，一种新型的NADPH传感器的晶体结构，并发现它形成一个不对称的二聚体，只有一个亚基被NADPH分子占据，两个亚基具有显着不同的构象。为了研究NADPH对HSCARG结构和功能的影响，我们构建了一系列HSCARG突变体，以消除NADPH结合能力。通过X射线晶体学解析了两个突变体R37 A和Y81 A的蛋白质结构。通过动态光散射研究了野生型和突变型HSCARG的二聚化。还比较了野生型和突变型HSCARG的功能之间的差异。我们的研究结果表明，NADPH的结合是必要的HSCARG形成一个稳定的不对称二聚体。的单体突变体的构象是类似的野生型HSCARG中的NADPH结合的分子I，虽然一些构象变化被发现在NADPH结合位点。此外，我们还注意到，NADPH结合能力的消除改变了HSCARG在细胞中的分布，并且与野生型HSCARG相比，这些没有NADPH的突变体与氨基琥珀酸合成酶的关联更强。这些数据表明，NADPH的功能作为HSCARG的结构和功能的变构调节剂。HSCARG作为一种氧化还原传感器，响应细胞内NADPH/NADP（+）比值的变化，与NADPH缔合和解离，形成新的动态平衡。这种平衡反过来又会改变蛋白质分子的二聚化平衡，从而控制HSCARG的调节功能。(C)2009爱思唯尔有限公司版权所有。
NADP(H) is an important cofactor that controls many fundamental cellular processes. We have determined the crystal structure of HSCARG, a novel NADPH sensor, and found that it forms an asymmetrical dimer with only one subunit occupied by an NADPH molecule, and the two subunits have dramatically different conformations. To study the role of NADPH in affecting the structure and function of HSCARG, here, we constructed a series of HSCARG mutants to abolish NADPH binding ability. Protein structures of two mutants, R37A and Y81A, were solved by X-ray crystallography. The dimerization of wild-type and mutant HSCARG was studied by dynamic light scattering. Differences between the function of wild-type and mutant HSCARG were also compared. Our results show that binding of NADPH is necessary for HSCARG to form a stable asymmetric dimer. The conformation of the monomeric mutants was similar to that of NADPH-bound Molecule I in wild-type HSCARG, although some conformational changes were found in the NADPH binding site. Furthermore, we also noticed that abolition of NADPH binding ability changes the distribution of HSCARG in the cell and that these mutants without NADPH are more strongly associated with argininosuccinate synthetase as compared with wild-type HSCARG. These data suggest that NADPH functions as an allosteric regulator of the structure and function of HSCARG. In response to the changes in the NADPH/NADP(+) ratio within cells, HSCARG, as a redox sensor, associates and dissociates with NADPH to form a new dynamic equilibrium. This equilibrium, in turn, will tip the dimerization balance of the protein molecule and consequently controls the regulatory function of HSCARG. (C) 2009 Elsevier Ltd. All rights reserved.