Electronic absorption, EPR, and resonance raman spectroscopy of CooA, a CO-sensing transcription activator from R. rubrum, reveals a five-coordinate NO-heme.
Electronic absorption, EPR, and resonance raman spectroscopy of CooA, a CO-sensing transcription activator from R. rubrum, reveals a five-coordinate NO-heme.
复制标题
CooA（一种来自 R. rubrum 的 CO 感应转录激活剂）的电子吸收、EPR 和共振拉曼光谱揭示了五配位的 NO-血红素。
DOI：
10.1021/bi991378g
复制
发表时间：
2000
期刊：
影响因子：
2.9
通讯作者：
Spiro,TG
中科院分区：
文献类型：
--
作者：
Reynolds,MF;Parks,RB;Burstyn,JN;Shelver,D;Thorsteinsson,MV;Kerby,RL;Roberts,GP;Vogel,KM;Spiro,TG
电子吸收光谱、EPR和共振拉曼光谱研究表明，来自红杜鹃的CO敏感转录调节因子CooA与NO反应形成一个五配位的NO-血红素。因此，NO必须从六配位的低自旋Fe（II）CooA中置换两个血红素配体，形成五配位的Fe（II）CooA（NO）。相反，CO从Fe（II）CooA置换单个血红素配体以形成六配位Fe（II）CooA（CO）。在一系列常见的血红素结合配体中，只有CO和NO能够与野生型CooA的血红素结合;咪唑、叠氮阴离子和氰化物阴离子对血红素吸收光谱没有影响。虽然NO与血红素结合并置换内源性配体，但NO不能诱导CooA与其靶DNA结合。因此，辅酶A的CO依赖性活化机制比从血红素铁中简单置换配体更复杂，因为NO不会触发DNA结合。这些观察结果表明，CooA血红素位点区分NO和生物相关信号CO。
Electronic absorption, EPR, and resonance Raman spectroscopies revealed that CooA, the CO-sensing transcriptional regulator fromRhodospirillum rubrum, reacts with NO to form a five-coordinate NO-heme. NO must therefore displace both of the heme ligands from six-coordinate, low-spin Fe(II)CooA in forming five-coordinate Fe(II)CooA(NO). CO, in contrast, displaces a single heme ligand from Fe(II)CooA to form six-coordinate Fe(II)CooA(CO). Of a series of common heme-binding ligands, only CO and NO were able to bind to the heme of wild-type CooA; imidazole, azide anion, and cyanide anion had no effect on the heme absorption spectrum. Although NO binds to the heme and displaces the endogenous ligands, NO was not able to induce CooA to bind to its target DNA. The mechanism of CO-dependent activation of CooA is thus more complex than simple displacement of a ligand from the heme iron since NO does not trigger DNA binding. These observations suggest that the CooA heme site discriminates between NO and the biologically relevant signal, CO.