Botany Department, The University of Georgia, Athens, Georgia 30602.
Plant Physiol. 1984 Jan;74(1):152-60. doi: 10.1104/pp.74.1.152.
When soybean Glycine max var Wayne seedlings are shifted from a normal growth temperature of 28 degrees C up to 40 degrees C (heat shock or HS), there is a dramatic change in protein synthesis. A new set of proteins known as heat shock proteins (HSPs) is produced and normal protein synthesis is greatly reduced. A brief 10-minute exposure to 45 degrees C followed by incubation at 28 degrees C also results in the synthesis of HSPs. Prolonged incubation (e.g. 1-2 hours) at 45 degrees C results in greatly impaired protein synthesis and seedling death. However, a pretreatment at 40 degrees C or a brief (10-minute) pulse treatment at 45 degrees C followed by a 28 degrees C incubation provide protection (thermal tolerance) to a subsequent exposure at 45 degrees C. Maximum thermoprotection is achieved by a 2-hour 40 degrees C pretreatment or after 2 hours at 28 degrees C with a prior 10-minute 45 degrees C exposure. Arsenite treatment (50 micromolar for 3 hours) also induces the synthesis of HSP-like proteins, and also provides thermoprotection to a 45 degrees C HS; thus, there is a strong positive correlation between the accumulation of HSPs and the acquisition of thermal tolerance under a range of conditions.During 40 degrees C HS, some HSPs become localized and stably associated with purified organelle fractions (e.g. nuclei, mitochondria, and ribosomes) while others do not. A chase at 28 degrees C results in the gradual loss over a 4-hour period of the HSPs from the organelle fractions, but the HSPs remain selectively localized during a 40 degrees C chase period. If the seedlings are subjected to a second HS after a 28 degrees C chase, the HSPs rapidly (complete within 15 minute) relocalize in the organelle fractions. The relative amount of the HSPs which relocalize during a second HS increases with higher temperatures from 40 degrees C to 45 degrees C. Proteins induced by arsenite treatment are not selectively localized with organelle fractions at 28 degrees C but become organelle-associated during a subsequent HS at 40 degrees C.
当大豆 Glycine max var Wayne 幼苗从正常生长温度 28°C 升高到 40°C（热休克或 HS）时，蛋白质合成会发生剧烈变化。一组新的蛋白质，即热休克蛋白（HSPs）被产生，正常的蛋白质合成大大减少。短暂暴露于 45°C 10 分钟，然后在 28°C 下孵育，也会导致 HSPs 的合成。在 45°C 下长时间孵育（例如 1-2 小时）会导致蛋白质合成严重受损和幼苗死亡。然而，在 40°C 下预处理或在 45°C 下短暂（10 分钟）脉冲处理后在 28°C 下孵育会为随后在 45°C 下的暴露提供保护（耐热性）。通过 2 小时 40°C 预处理或 28°C 下 2 小时预处理，然后在 45°C 下 10 分钟暴露，可获得最大的热保护。亚砷酸盐处理（3 小时 50 微摩尔）也会诱导 HSP 样蛋白的合成，并为 45°C HS 提供热保护；因此，在各种条件下，HSP 的积累与获得耐热性之间存在很强的正相关关系。在 40°C HS 期间，一些 HSPs 定位于并与纯化的细胞器部分（如核、线粒体和核糖体）稳定相关联，而其他 HSPs 则不相关联。在 28°C 下追踪会导致 HSPs 在 4 小时内逐渐从细胞器部分丢失，但在 40°C 追踪期间 HSPs 仍然选择性地定位于细胞器部分。如果幼苗在 28°C 追踪后再次接受 HS，则 HSPs 会在 15 分钟内迅速（完全）重新定位于细胞器部分。在第二次 HS 期间重新定位的 HSPs 的相对量随温度从 40°C 升高到 45°C 而增加。亚砷酸盐处理诱导的蛋白质在 28°C 下与细胞器部分没有选择性地定位，但在随后的 40°C HS 下成为细胞器相关。
