The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.
The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.
复制标题
ToxR 的两个方面：霍乱弧菌中 ompU 的激活剂、toxT 的共同调节剂。
DOI：
10.1111/j.1365-2958.2011.07681.x
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发表时间：
2011
影响因子：
3.6
通讯作者：
Krukonis,EricS
中科院分区：
文献类型：
--
作者：
Morgan,SarahJ;Felek,Suleyman;Gadwal,Shilpa;Koropatkin,NicoleM;Perry,JeffreyW;Bryson,AlysonB;Krukonis,EricS
霍乱弧菌的ToxR直接激活ompU启动子，但需要第二个激活子TcpP激活toxT启动子，ompU编码一个孔蛋白，而toxT编码转录因子ToxT，后者激活V。霍乱毒力基因包括霍乱毒素和毒素共调节菌毛。使用anompU-sacB转录融合，鉴定了编码ompU启动子激活缺陷的ToxR分子的toxR突变等位基因。许多毒素R突变体的缺陷ompU活化影响残基参与DNA结合。还测试了ompU激活缺陷的突变体的toxT启动子激活。ToxR-F69 A和ToxR-V71 A都在ToxR的α环中，优先缺陷于ompU激活，ToxR-V71 A几乎完全缺陷。从ompU-sacB选择的六个突变体显示出比ompU激活更严重的缺陷。除了一个之外，所有受影响的残基都映射到ToxR的翼螺旋-转角-螺旋的翼域。一些优先影响toxT活化的ToxR突变体具有部分DNA结合缺陷，并且一个突变体ToxR-P101 L与TcpP的相互作用改变。这些数据表明，虽然ToxR α环中的某些残基被用来激活ompU启动子，但ToxR的翼区结构域有助于启动子结合和ToxR/TcpP相互作用，从而促进ToxT激活。
ToxR ofVibrio choleraedirectly activates theompUpromoter, but requires a second activator, TcpP to activate thetoxTpromoter.ompUencodes a porin, whiletoxTencodes the transcription factor, ToxT, which activatesV. choleraevirulence genes including cholera toxin and the toxin co‐regulated pilus. Using anompU‐sacBtranscriptional fusion,toxRmutant alleles were identified that encode ToxR molecules defective forompUpromoter activation. ManytoxRmutants defective forompUactivation affected residues involved in DNA binding. Mutants defective forompUactivation were also tested for activation of thetoxTpromoter. ToxR‐F69A and ToxR‐V71A, both in the α‐loop of ToxR, were preferentially defective forompUactivation, with ToxR‐V71A nearly completely defective. Six mutants from theompU‐sacBselection showed more dramatic defects intoxTactivation thanompUactivation. All but one of the affected residues map to the wing domain of the winged helix–turn–helix of ToxR. Some ToxR mutants preferentially affectingtoxTactivation had partial DNA‐binding defects, and one mutant, ToxR‐P101L, had altered interactions with TcpP. These data suggest that while certain residues in the α‐loop of ToxR are utilized to activate theompUpromoter, the wing domain of ToxR contributes to both promoter binding and ToxR/TcpP interaction facilitatingtoxTactivation.