Hsc66 and Hsc20, a new heat shock cognate molecular chaperone system from Escherichia coli.
Hsc66 and Hsc20, a new heat shock cognate molecular chaperone system from Escherichia coli.
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Hsc66 和 Hsc20，一种来自大肠杆菌的新型热休克同源分子伴侣系统。
DOI：
10.1002/pro.5560060511
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Ta,DT
中科院分区：
文献类型：
--
作者：
Vickery,LE;Silberg,JJ;Ta,DT
ThehscAandhscBgenes ofEscherichia coliencode novel chaperone and co‐chaperone proteins, designated Hsc66 and Hsc20, respectively. We have overproduced and purified Hsc66 and Hsc20 in high yield inE. coliand describe their initial characterization including absorbance, fluorescence, and circular dichroism spectra. Immunoblot analyses ofE. colicultures using antisera to Hsc66 and Hsc20 raised in rabbits establish that Hsc66 and Hsc20 are constitutively expressed at levels corresponding to cell concentrations ˜20 μM and ˜10 μM, respectively. The levels do not change appreciably following heat shock (44°C), but a small increase in Hsc20 is observed following a shift to 10°C. Purified Hsc66 exhibits a low intrinsic ATPase activity (˜0.6 min−1at 37° C), and Hsc20 was found to stimulate this activity up to 3.8‐fold with half‐maximal stimulation at a concentration ˜5 μM. These findings suggest that Hsc66 and Hsc20 comprise a molecular chaperone system similar to the prokaryotic DnaK/DnaJ and eukaryotic hsp70/hsp40 systems. Sequence differences between Hsc66 and Hsc20 compared to other members of this chaperone family, however, suggest that the Hsc66/Hsc20 system will display different peptide binding specificity and that it is likely to be subject to different regulatory mechanisms. The high level of constitutive expression and the lack of a major response to temperature changes suggest that Hsc66 and Hsc20 play an important cellular role(s) under non‐stress conditions.
