STRUCTURAL STUDIES ON THE MASTER REGULATOR OF CARBON CATABOLITE CONTROL IN GRAM

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。所列机构为 中心，不一定是研究者的机构。 碳分解代谢物抑制（CCR）是一种全球性的调节机制，使细菌能够优先利用其环境中可用的碳源。在大肠大肠杆菌和其他肠道细菌，CCR已被广泛研究，因为J.莫诺首先指出，E。大肠杆菌更喜欢葡萄糖作为碳源。后来表明，这些细菌中的CCR是通过DNA结合激活蛋白，cAMP受体蛋白（CRP）介导的，其在cAMP存在下被诱导结合DNA。 最近已经证明，既不含CRP也不含cAMP的革兰氏阳性细菌使用完全不同的CCR机制。具体地说，在这些细菌中，CCR的主要调节因子是转录因子，碳分解代谢物蛋白A（CcpA），LacI/GalR家族的成员。强调其多效性作用，这种蛋白质调节芽孢杆菌中超过200个基因，占整个芽孢杆菌基因组的8%以上。为了响应高水平的果糖1，6-二磷酸，HPr激酶在丝氨酸46处磷酸化含组氨酸蛋白（HPr）。HPr的Ser 46磷酸化形式结合CcpA并激活以结合其在大CCR操纵子中的Cre DNA位点。 因此，磷酸丝氨酸46 HPr作为CcpA的辅阻遏物发挥作用，提供了LacI/GalR成员的唯一例子，该成员通过结合另一种蛋白质而被激活以结合DNA。为了剖析磷酸丝氨酸46 Hpr作为辅阻遏物发挥作用并与CcpA特异性相互作用的分子机制，我们从B获得了三元CcpA-phosphoSer 46 HPr-Cre位点的晶体。巨大的我们还生长了晶体的CcpA在磷酸丝氨酸46 Hpr或Cre的情况下，以获得非激活以及激活构象状态的CcpA。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Carbon Catabolite Repression (CCR) is the global regulatory mechanism enabling bacteria to preferentially utilize the carbon source that is available in their environment. In E. coli and other enteric bacteria, CCR has been extensively studied since J. Monod first noted that E. coli prefer glucose as a carbon source. It was later shown that CCR in these bacteria is mediated through the DNA binding activator protein, cAMP receptor protein (CRP), which is induced to bind DNA in the presence of cAMP. It has more recently been demonstrated that Gram positive bacteria, which contain neither CRP nor cAMP, use an entirely different mechanism of CCR Specifically, in these bacteria, the master regulator of CCR is the transcription factor, the Carbon catabolite protein A (CcpA), a member of the LacI/GalR family. Underscoring its pleiotropic role, this protein regulates over 200 genes in Bacilli, accounting for over 8% of the entire Bacilli genome. In response to high levels of fructose 1,6-bisphosphate, HPr kinase phosphorylates the histidine-containing protein (HPr) at Serine 46. The Ser46 phosphorylated form of HPr binds CcpA and activates to bind its Cre DNA sites in the large CCR operon. Thus, phosphoSer46HPr functions as a corepressor for CcpA, providing the only example of a LacI/GalR member that is activated to bind DNA by binding another protein. To dissect the molecular mechanism whereby phosphoSer46Hpr can function as a corepressor and specifically interact with CcpA, we have obtained crystals of the ternary CcpA-phosphoSer46HPr-Cre site from B. megaterium. We have also grown crystals of CcpA in the absence of phosphoSer46Hpr or the Cre in order to obtain the non-activated as well as the activated conformational state of CcpA.