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首页> 外文期刊>Journal of Molecular Biology >THE ZINC COORDINATION SITE OF THE BACTERIOPHAGE MU TRANSLATIONAL ACTIVATOR PROTEIN, COM
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THE ZINC COORDINATION SITE OF THE BACTERIOPHAGE MU TRANSLATIONAL ACTIVATOR PROTEIN, COM

机译：噬菌体MU翻译活化蛋白，COM的锌配位位点

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The bacteriophage Mu Com protein is a small ''zinc finger-like'' protein that binds a specific site in com-mom operon mRNA and activates translation of the mom open-reading-frame. Com contains six cysteine and five histidine residues that have the potential to form several alternative zinc-finger-like motifs. We have used oligonucleotide site-directed mutagenesis to individually alter each of these amino acids (Cys to Ser, and His to Asn or Gln) and tested the various forms of Com for their ability to function in vivo. We observed that mutation of any one of the four N-terminal cysteine residues (Cys-6, 9, 26 or 29) resulted in loss of Com activity. The Com protein requires zinc in order to fold into its functional tertiary structure, as demonstrated by characteristic H-1 nuclear magnetic resonance (NMR) chemical shifts. H-1 chemical shifts revert to random coil values in the presence of the metal chelator EDTA. The metal-binding specificity and thermal stability of Com also has been investigated using H-1 NMR. We report the use of Cd-113 NMR, H-1-Cd-113 heteronuclear spin-echo difference spectroscopy HSED and Zn extended X-ray absorption fine structure spectroscopy EXAFS to determine the zinc/protein stoichiometry as 1:1 and the ligand environment as tetrathiolate. Comparative NMR spectra of Com mutants C6S and C39S suggest position 6 is involved in zinc coordination, while position 39 is not metal-liganded. These studies indicate that the metal coordination, site of Corn is a four-cysteine complex, involving residues 9, 26 and 29. [References: 57]
机译：噬菌体Mu Com蛋白是一种小的“锌指样”蛋白，与com-mom操纵子mRNA中的特定位点结合并激活妈妈的开放阅读框。 Com含有六个半胱氨酸和五个组氨酸残基，它们有可能形成几种替代的锌指样基序。我们已经使用寡核苷酸定点诱变来单独改变每个氨基酸（Cys到Ser，His到Asn或Gln），并测试了各种形式的Com在体内的功能。我们观察到，四个N端半胱氨酸残基中的任何一个（Cys-6、9、26或29）突变都会导致Com活性降低。 Com蛋白需要锌才能折叠成其功能性三级结构，如特征性H-1核磁共振（NMR）化学位移所证明。在存在金属螯合剂EDTA的情况下，H-1化学位移恢复为随机线圈值。还使用H-1 NMR研究了Com的金属结合特异性和热稳定性。我们报告了使用Cd-113 NMR，H-1-Cd-113异核自旋回波差异光谱HSED和Zn扩展X射线吸收精细结构光谱EXAFS来确定锌/蛋白质化学计量比为1：1和配体环境为四硫醇盐。 Com突变体C6S和C39S的比较NMR光谱表明，位置6与锌配位有关，而位置39没有金属配体。这些研究表明玉米的金属配位位点是一个四半胱氨酸复合物，涉及残基9、26和29。[参考文献：57]

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