Tandem DctD-binding sites of the Rhizobium meliloti dctA upstream activating sequence are essential for optimal function despite a 50- to 100-fold difference in affinity for DctD.
Tandem DctD-binding sites of the Rhizobium meliloti dctA upstream activating sequence are essential for optimal function despite a 50- to 100-fold difference in affinity for DctD.
复制标题
尽管对 DctD 的亲和力存在 50 至 100 倍的差异，苜蓿根瘤菌 dctA 上游激活序列的串联 DctD 结合位点对于实现最佳功能至关重要。
DOI：
10.1111/j.1365-2958.1992.tb01783.x
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发表时间：
1992
影响因子：
3.6
通讯作者：
Nixon,BT
中科院分区：
文献类型：
--
作者：
Ledebur,H;Nixon,BT
TheRhizobium melilotgenesdctBanddctDpositively regulate the expression ofdctA, which encodes a C4‐dicarboxylate transport protein. Here we characterize an element (UAS) located upstream ofdctAthat has tandem binding sites for thedctDgene product (DctD). At relatively low concentrations of active DctD, the element activateddctAtranscription, but at relatively high concentrations of DctD it was inhibitory. The UAS failed to function when placed further upstream ofdctA.Both DctD‐binding sites were required for optimal UAS function, despite a 50‐ to 100‐fold difference in binding affinities. Moving the promoter distal binding site 5 bp further upstream was functionally equivalent to its deletion. Based on these data, we hypothesize that the α54‐dependent activator DctD binds co‐operatively to the R.meliloti dctAUAS, and that occupancy of both sites is required for maximal activation ofdctA.
