Molecular Interactions Involved In Gal Repression

我们研究了Gal阻遏的相互作用，使用的分析ultracentrage。阻遏环显然涉及GalR与DNA上的半乳糖操纵子位点的结合，但发现HU的存在对于抑制的发生是必要的。我们首先分别研究了HU和GalR的自缔合性质，以建立自缔合的模式和强度。随后研究GalR与含有两个半乳糖操纵子之一的寡核苷酸（29个碱基对的寡核苷酸）的结合。最后，添加HU，并使用先前建立的缔合模式和它们的缔合强度，我们推断一对HU单体与具有GalR二聚体的寡核苷酸的复合物结合。结合强度也被建立，结果与能量转移荧光和偏振各向异性测量得到的结果是一致的。

We studied the interaction involved in Gal repression using the analytical ultracentrifuge. The repression loop apparently involves binding of GalR to the galactose operator sites on the DNA but for suppression to occur the presence of HU has been found to be necessary. We studied first the self association properties of HU and GalR separately to establish the patterns and strengths of the self-associations. This was followed by the study of the binding of GalR to the oligonucleotide containing one of the two galactose operators (a 29 base-pair oligonucleotide). Finally HU was added and using the previously established association patterns and their association strengths we deduced that a pair of HU monomers binds to the complex of the oligonucleotide with a GalR dimer. The association strength was also established and the results were consistent with those obtained by energy transfer fluorescence and polarization anisotropy measurements.