CRYSTAL STRUCTURE OF MOLECULAR CHAPERONE, HSC20

分子伴侣在蛋白质折叠、运输中起着关键作用 和跨膜，以及对应激刺激的反应。HSC20是 新近发现的一种DNAJ型辅伴侣蛋白 大肠杆菌中的操纵子，编码DNAK/hsp70型伴侣。不是 DNAJ辅助伴侣的结构已经确定，尽管 的N-末端‘J结构域(100个残基)的溶液MNR结构 DNAJ揭示了二级结构特征。我们成功地 Hsc20的高效表达、纯化和结晶。因此，Hsc20可以 提供了第一个完整的高分辨率晶体结构 这类蛋白质。天然蛋白质的衍射数据有 用传统的X射线源获得了2.6A的能量。我们准备了 引入半胱氨酸残基的两个重原子衍生物 蛋白质诱变。汞标记晶体太小，不能 使用我们的x射线源提供用于MIR定相的数据，我们寻求 使用同步辐射确定更高分辨率的数据 消息来源。

Molecular chaperones play key roles in protein folding, transport and across membranes, and in response to stressful stimuli. Hsc20 is a DnaJ-type cochaperone protein encoded in a recently discovered operon in E. coli which encodes a DnaK/hsp70type chaperone. No structure for a DnaJ co-chaperone has been determined although a solution MNR structure of the N-terminal 'Jdomain (100 residues) of DnaJ has revealed secondary structure features.We succeeded in overexpressing, purifying and crystallizing Hsc20. Thus, Hsc20 could provide the first complete high resolution crystal structure for proteins of this class. Diffraction data for the native protein have been obtained to 2.6A using conventional x-ray sources. We prepared two heavy atom derivatives by introducing cysteine residues into protein mutagenesis. Crystals of Hg-labeled crystals are too small to provide data for MIR phasing using our x-ray source, and we seek to determine higher resolution data using the synchrotron radiation source.