Cu(I)-mediated Allosteric Switching in a Copper-sensing Operon Repressor (CsoR)
Cu(I)-mediated Allosteric Switching in a Copper-sensing Operon Repressor (CsoR)
复制标题
DOI：
10.1074/jbc.m114.556704
复制
发表时间：
2014-07-11
影响因子：
4.8
通讯作者：
Giedroc, David P.
中科院分区：
文献类型：
--
作者：
Chang, Feng-Ming James;Coyne, H. Jerome;Giedroc, David P.
铜敏感操纵子阻遏子（CsoR）是细菌金属调节蛋白的主要Cu（I）敏感家族的代表，其已经进化以防止细胞质铜毒性。目前尚不清楚Cu（I）与四聚体CsoRs的结合如何介导铜抗性基因的转录去抑制。227 DUF 156蛋白质成员，包括生化或结构特征的CsoR/RcnR阻遏物的系统发育分析表明，嗜热土芽孢杆菌（Gt）CsoR的特征在于这里是代表的CsoRs从致病性杆菌李斯特菌和炭疽杆菌。Cu（I）结合的Gt CsoR的2.56结构揭示了Cu（I）结合在两个保守的铜连接残基之间的α 2-螺旋中诱导扭结，并在Cu（I）结合位点上折叠N-末端尾（残基12-19）。Gt CsoR的NMR研究表明，该尾部在脱辅基状态下是柔性的，这些动力学在Cu（I）结合时淬灭。对N-末端截短的Gt CsoR（Delta 2-10）的小角X射线散射实验表明，Cu（I）结合的四聚体在流体动力学上比apo态更紧凑。这些研究结果的其他CsoR/RcnR抑制剂的变构机制的影响进行了讨论。
The copper-sensing operon repressor (CsoR) is representative of a major Cu(I)-sensing family of bacterial metalloregulatory proteins that has evolved to prevent cytoplasmic copper toxicity. It is unknown how Cu(I) binding to tetrameric CsoRs mediates transcriptional derepression of copper resistance genes. A phylogenetic analysis of 227 DUF156 protein members, including biochemically or structurally characterized CsoR/RcnR repressors, reveals that Geobacillus thermodenitrificans (Gt) CsoR characterized here is representative of CsoRs from pathogenic bacilli Listeria monocytogenes and Bacillus anthracis. The 2.56 structure of Cu(I)-bound Gt CsoR reveals that Cu(I) binding induces a kink in the alpha 2-helix between two conserved copper-ligating residues and folds an N-terminal tail (residues 12-19) over the Cu(I) binding site. NMR studies of Gt CsoR reveal that this tail is flexible in the apo-state with these dynamics quenched upon Cu(I) binding. Small angle x-ray scattering experiments on an N-terminally truncated Gt CsoR (Delta 2-10) reveal that the Cu(I)-bound tetramer is hydrodynamically more compact than is the apo-state. The implications of these findings for the allosteric mechanisms of other CsoR/RcnR repressors are discussed.