Structures of the Escherichia coli transcription activator and regulator of diauxie, XylR: an AraC DNA-binding family member with a LacI/GalR ligand-binding domain.
Structures of the Escherichia coli transcription activator and regulator of diauxie, XylR: an AraC DNA-binding family member with a LacI/GalR ligand-binding domain.
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DOI：
10.1093/nar/gks1207
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发表时间：
2013-02-01
影响因子：
14.9
通讯作者：
Schumacher MA
中科院分区：
文献类型：
--
作者：
Ni L;Tonthat NK;Chinnam N;Schumacher MA
在缺乏其首选碳源葡萄糖的情况下，大肠杆菌可以快速转换为 L-阿拉伯糖和 d-木糖的代谢，这一过程称为碳分解代谢物抑制。 L-阿拉伯糖和 d-木糖消耗所需基因的转录受到糖响应转录因子 AraC 和 XylR 的调节。大肠杆菌是通过半纤维素代谢生产生物燃料的有前途的候选者，半纤维素由d-木糖和L-阿拉伯糖组成。了解 L-阿拉伯糖/D-木糖调控网络是此类生物催化剂开发的关键。与 AraC 不同，AraC 是一种经过充分研究的蛋白质，但人们对 XylR 知之甚少。为了深入了解 XylR 功能，我们进行了生化和结构研究。 XylR 包含 C 端 AraC 样结构域。然而，其 N 端 d-木糖结合结构域包含周质结合蛋白 (PBP) 折叠，与 LacI/GalR 转录调节因子具有结构同源性。与 LacI/GalR 蛋白一样，XylR PBP 结构域介导二聚化。然而，与以平行、侧对侧方式二聚化的 LacI/GalR 蛋白不同，XylR PBP 二聚体是反平行的。引人注目的是，d-木糖与该结构域的结合导致二聚体界面处的螺旋到链的转变，从而重新定位两个 DNA 结合结构域，使它们能够结合并环化远处的操纵位点。因此，综合数据揭示了新的 DNA 结合蛋白家族的配体诱导激活机制。
Escherichia coli can rapidly switch to the metabolism of l-arabinose and d-xylose in the absence of its preferred carbon source, glucose, in a process called carbon catabolite repression. Transcription of the genes required for l-arabinose and d-xylose consumption is regulated by the sugar-responsive transcription factors, AraC and XylR. E. coli represents a promising candidate for biofuel production through the metabolism of hemicellulose, which is composed of d-xylose and l-arabinose. Understanding the l-arabinose/d-xylose regulatory network is key for such biocatalyst development. Unlike AraC, which is a well-studied protein, little is known about XylR. To gain insight into XylR function, we performed biochemical and structural studies. XylR contains a C-terminal AraC-like domain. However, its N-terminal d-xylose-binding domain contains a periplasmic-binding protein (PBP) fold with structural homology to LacI/GalR transcription regulators. Like LacI/GalR proteins, the XylR PBP domain mediates dimerization. However, unlike LacI/GalR proteins, which dimerize in a parallel, side-to-side manner, XylR PBP dimers are antiparallel. Strikingly, d-xylose binding to this domain results in a helix to strand transition at the dimer interface that reorients both DNA-binding domains, allowing them to bind and loop distant operator sites. Thus, the combined data reveal the ligand-induced activation mechanism of a new family of DNA-binding proteins.
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DOI：
10.1073/pnas.95.18.10413
发表时间：
1998-09-01
影响因子：
11.1
作者：
Rhee, S;Martin, RG;Davies, DR
通讯作者：
Davies, DR
影响因子：
4
作者：
Schleif, R
通讯作者：
Schleif, R
DOI：
10.1107/s090744499900846x
发表时间：
1999-10-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Leslie, AGW
通讯作者：
Leslie, AGW
影响因子：
64.5
作者：
Schumacher, MA;Allen, GS;Brennan, RG
通讯作者：
Brennan, RG
影响因子：
64.5
作者：
SCHUMACHER, MA;CHOI, KY;BRENNAN, RG
通讯作者：
BRENNAN, RG