Identification of a putative metal binding site in a new family of metalloregulatory proteins.
Identification of a putative metal binding site in a new family of metalloregulatory proteins.
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发表时间：
1994-08
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通讯作者：
W. Shi;J. Wu;B. Rosen
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作者：
W. Shi;J. Wu;B. Rosen
Ars操纵子的转录受ArsR抑制因子的负调控，并受亚砷酸盐和亚硫酸盐的诱导。通过羟胺诱变，分离到4个arsR突变体，其中3个突变株对诱变剂不敏感：C32Y、C32F和C34Y。三种改变的蛋白质中的每一种仍然与ARS操纵子特异结合，但诱导剂在影响改变的蛋白质从DNA中释放的效果较差。每个突变的arsR基因都带有一个由ars启动子控制的报告基因，抑制了报告基因的表达，而诱导剂的加入并不能解除抑制。这些结果表明，改变的ArsR蛋白在诱导物结合部位存在缺陷。第四个arsR突变导致H50Y改变，产生结构性表达。His-50位于ArsR蛋白的螺旋-转角-螺旋区域。我们认为，ArsR蛋白中的半胱氨酸Cys-32和Cys-34构成了ArsR金属调节蛋白家族成员中发现的金属结合基序的一部分。
The transcription of the ars operon is negatively controlled by the ArsR repressor and induced by arsenite and antimonite. Using hydroxylamine mutagenesis, four arsR mutants were isolated; three were selected for inability to respond to inducers: C32Y, C32F, and C34Y. Each of the three altered proteins still bound specifically to the ars operator, but inducers were less effective in effecting the release of the altered proteins from the DNA. Each of the mutant arsR genes in trans with a reporter gene controlled by the ars promoter repressed expression of the reporter gene, and addition of inducer did not relieve repression. These results suggest that the altered ArsR proteins are defective in the inducer binding site. The fourth arsR mutation, resulting in a H50Y alteration, produced constitutive expression. His-50 is located within a putative helix-turn-helix region of the ArsR protein. We propose that cysteines Cys-32 and Cys-34 in the ArsR protein comprise part of a metal binding motif found in members of the ArsR family of metalloregulatory proteins.