Structural basis for allosteric control of the transcription regulator CcpA by the phosphoprotein HPr-Ser46-P
Structural basis for allosteric control of the transcription regulator CcpA by the phosphoprotein HPr-Ser46-P
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DOI：
10.1016/j.cell.2004.08.027
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发表时间：
2004-09-17
期刊：
影响因子：
64.5
通讯作者：
Brennan, RG
中科院分区：
文献类型：
--
作者：
Schumacher, MA;Allen, GS;Brennan, RG
碳代谢产物阻遏（CCR）是细菌最基本的环境感知机制之一，并通过建立碳代谢的优先级来赋予竞争优势。在革兰氏阳性细菌中，CCR的主要转录调节因子是CcpA。CcpA是Lacl-GaIR家族成员，其采用在葡萄糖充足条件下形成的磷蛋白HPr-Ser 46-P作为变构辅阻遏物。在这里，我们报告的巨大芽孢杆菌apoCcpA和CcpA-（HPr-Ser 46-P）-DNA复合物的结构。这些结构表明，HPr-Ser 46-P介导一种新的双组分变构DNA结合激活机制，涉及CcpA亚结构域的旋转和重新定位的非定点残基Thr 61，这导致并列的DNA结合区域允许在同源DNA的存在下形成“铰链”螺旋。CcpA-（HPr-Ser 46-P）-cre复合物的结构还揭示了CcpA家族特异性与HPr-Ser 46-P残基Ser 46-P和His 15的相互作用划分高能CCR和低能PTS途径的优雅机制，后者需要HPr-His 15-P。
Carbon catabolite repression (CCR) is one of the most fundamental environmental-sensing mechanisms in bacteria and imparts competitive advantage by establishing priorities in carbon metabolism. In gram-positive bacteria, the master transcription regulator of CCR is CcpA. CcpA is a Lacl-GaIR family member that employs, as an allosteric corepressor, the phosphoprotein HPr-Ser46-P, which is formed in glucose-replete conditions. Here we report structures of the Bacillus megaterium apoCcpA and a CcpA-(HPr-Ser46-P)-DNA complex. These structures reveal that HPr-Ser46-P mediates a novel two-component allosteric DNA binding activation mechanism that involves both rotation of the CcpA subdomains and relocation of pivot-point residue Thr61, which leads to juxtaposition of the DNA binding regions permitting "hinge" helix formation in the presence of cognate DNA. The structure of the CcpA-(HPr-Ser46-P)-cre complex also reveals the elegant mechanism by which CcpA family-specific interactions with HPr-Ser46-P residues Ser46-P and His15 partition the high-energy CCR and low-energy PTS pathways, the latter requiring HPr-His15-P.