Ligand-binding pocket bridges DNA-binding and dimerization domains of the urate-responsive MarR homologue MftR from Burkholderia thailandensis.
Ligand-binding pocket bridges DNA-binding and dimerization domains of the urate-responsive MarR homologue MftR from Burkholderia thailandensis.
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DOI：
10.1021/bi500219t
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发表时间：
2014-07-15
期刊：
影响因子：
2.9
通讯作者：
Grove A
中科院分区：
文献类型：
--
作者：
Gupta A;Grove A
多种抗生素耐药调节剂（MarR）家族的成员通常通过对特定配体的反应来调节基因活性。在没有配体的情况下，大多数MarR蛋白起抑制作用，而配体结合导致DNA结合减弱，从而增加基因表达。先前，我们已经证明尿酸盐是MftR（主要促进剂运输调节剂）的配体，这是由土壤细菌泰国伯克霍尔德菌编码的。我们在这里发现，在尿酸存在的情况下，mftR和编码主要促进物转运蛋白的分化导向基因mftP都被上调。MftR结合MftR - mftp基因间区的两个同源位点，对尿酸具有相同的亲和力和敏感性。先前报道的与耐辐射球菌（Deinococcus radiudurans） HucR和放射根瘤菌（Rhizobium radiobacter PecS）尿酸结合有关的四个保守残基的突变显著降低了蛋白质稳定性和DNA结合亲和力，但没有降低配体结合。这些数据表明，与HucR和PecS的配体结合相关的残基具有结构作用，而MftR依赖于不同的配体结合残基。MftR呈现两步融化转变，表明二聚化区和dna结合区独立展开；尿酸盐结合或预测配体结合位点的突变导致一步展开转变。我们认为MftR在DNA结合叶和二聚体界面之间的间隙中与配体结合，但配体介导的DNA结合衰减机制与其他对DNA有反应的MarR同源物不同。由于MftR的DNA结合在37°C时减弱，我们的数据还表明，MftR通过减弱DNA结合和上调其控制下的基因来响应配体和热上移。
Members of the multiple antibiotic resistance regulator (MarR) family often regulate gene activity by responding to a specific ligand. In the absence of ligand, most MarR proteins function as repressors, while ligand binding causes attenuated DNA binding and therefore increased gene expression. Previously, we have shown that urate is a ligand for MftR (major facilitator transport regulator), which is encoded by the soil bacterium Burkholderia thailandensis. We show here that both mftR and the divergently oriented gene mftP encoding a major facilitator transport protein are upregulated in the presence of urate. MftR binds two cognate sites in the mftR-mftP intergenic region with equivalent affinity and sensitivity to urate. Mutagenesis of four conserved residues previously reported to be involved in urate binding to Deinococcus radiodurans HucR and Rhizobium radiobacter PecS significantly reduced protein stability and DNA binding affinity but not ligand binding. These data suggest that residues equivalent to those implicated in ligand binding to HucR and PecS serve structural roles and that MftR relies on distinct residues for ligand binding. MftR exhibits a two-step melting transition suggesting independent unfolding of the dimerization and DNA-binding regions; urate binding or mutations in the predicted ligand-binding sites result in one-step unfolding transitions. We suggest that MftR binds the ligand in a cleft between the DNA-binding lobes and the dimer interface but that the mechanism of ligand-mediated attenuation of DNA binding differs from that proposed for other urate-responsive MarR homologues. Since DNA binding by MftR is attenuated at 37 °C, our data also suggest that MftR responds to both ligand and a thermal upshift by attenuated DNA binding and upregulation of the genes under its control.
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影响因子：
14.9
作者：
Davis JR;Brown BL;Page R;Sello JK
通讯作者：
Sello JK
影响因子：
11.5
作者：
Li XZ;Nikaido H
通讯作者：
Nikaido H
DOI：
10.1073/pnas.102483199
发表时间：
2002-05-14
影响因子：
11.1
作者：
Fuangthong, M;Helmann, JD
通讯作者：
Helmann, JD
影响因子：
3.2
作者：
COHEN, SP;LEVY, SB;ROSNER, JL
通讯作者：
ROSNER, JL
影响因子：
3.2
作者：
Hommais, Florence;Oger-Desfeux, Christine;Reverchon, Sylvie
通讯作者：
Reverchon, Sylvie