Small heat shock proteins are molecular chaperones.
Small heat shock proteins are molecular chaperones.
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DOI：
10.1016/s0021-9258(18)53882-5
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发表时间：
1993-01
期刊：
影响因子：
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通讯作者：
U. Jakob;M. Gaestel;K. Engel;J. Buchner
中科院分区：
文献类型：
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作者：
U. Jakob;M. Gaestel;K. Engel;J. Buchner
分子量为 15-30 kDa 的小热休克蛋白 (sHsp) 普遍存在且保守。到目前为止，它们的功能仍然是个谜。热激条件下表达增加及其在高温下对细胞活力的保护作用表明它们可能在形成或维持胞浆蛋白天然构象中具有功能。为了验证这一假设，我们在体外研究了鼠 Hsp25、人 Hsp27 和牛 α-B-晶状体蛋白（与 sHsps 同源的眼晶状体蛋白）对柠檬酸合酶和 α-葡萄糖苷酶的展开和重折叠的影响。在这里，我们表明所有研究的 sHsp 在这些折叠反应中都充当分子伴侣。在化学计量下，它们最大限度地防止热激条件下柠檬酸合酶和α-葡萄糖苷酶的聚集并稳定蛋白质。此外，与 GroE 和 Hsp90 类似，它们在尿素变性后促进这些蛋白质的功能性重折叠。与展开和重折叠蛋白质的相互作用似乎不依赖于 ATP。
Small heat shock proteins (sHsp) with a molecular mass of 15-30 kDa are ubiquitous and conserved. Up to now their function has remained enigmatic. Increased expression under heat shock conditions and their protective effect on cell viability at elevated temperatures suggest that they may have a function in the formation or maintenance of the native conformation of cytosolic proteins. To test this hypothesis we studied the influence of murine Hsp25, human Hsp27, and bovine alpha-B-crystallin (an eye lens protein homologous to sHsps) on the unfolding and refolding of citrate synthase and alpha-glucosidase in vitro. Here we show that all sHsps investigated act as molecular chaperones in these folding reactions. At stoichiometric amounts they maximally prevent the aggregation of citrate synthase and alpha-glucosidase under heat shock conditions and stabilize the proteins. Furthermore, they promote the functional refolding of these proteins after urea denaturation similar to GroE and Hsp90. The interaction both with unfolding and refolding proteins seems to be ATP-independent.