Abnormal induction of heat shock proteins in an Escherichia coli mutant deficient in adenosylmethionine synthetase activity.
Abnormal induction of heat shock proteins in an Escherichia coli mutant deficient in adenosylmethionine synthetase activity.
复制标题
腺苷甲硫氨酸合成酶活性缺陷的大肠杆菌突变体中热休克蛋白的异常诱导。
DOI：
10.1128/jb.170.4.1582-1588.1988
复制
发表时间：
1988
影响因子：
3.2
通讯作者：
Neidhardt,FC
中科院分区：
文献类型：
--
作者：
Matthews,RG;Neidhardt,FC
大多数大肠杆菌原养型菌株在44摄氏度时对甲硫氨酸产生限制。其中S-腺苷甲硫氨酸合成酶活性水平仅为正常水平的10 - 20%的突变株（RG62 metK）在37 ℃下显示热休克蛋白之一，lysU基因产物，赖氨酰-tRNA合成酶II型的组成型表达。这些发现表明甲硫氨酸代谢和热休克之间可能存在联系。我们研究了热休克多肽在菌株RG62（metK）和其亲本，RG（metK+），从它是由自发突变的诱导。两种菌株的指数期培养物在从37 ° C转移到44 ° C后不久用[3H]亮氨酸脉冲标记，并通过二维电泳检查总细胞多肽。结果证实了先前报道的菌株RG62的lysU基因产物的组成型生产，但也揭示了17种热休克多肽中的2种（C14.7和G13.5）的诱导被显著抑制。另外，两种菌株的热休克诱导模式在时间和幅度上相似。用含有metK编码序列和启动子区的质粒pK8作为1.8-丝氨酸蛋白酶插入物转化突变菌株，恢复了C14.7和G13.5的正常诱导，但没有阻止该菌株生长所需的培养基中lysU基因产物的组成型表达。在菌株RG62中异常控制的三种热休克多肽是当在28 ℃下用异丙基-β-D-硫代半乳糖苷诱导htpR基因产物的快速合成时不被诱导的三种多肽（R. a. VanBogelen，M. a. Acton和F. C. Neidhardt，Genes Dev. 1：525 - 531，1987）。我们假设这三种多肽的诱导除了htpR基因产物的合成之外还涉及代谢信号，并且菌株RG62（metK）在温度升高时不能产生涉及C14.7和G13.5诱导的信号，并且即使在37 ℃下也产生与lysU诱导相关的信号。
Most prototrophic strains of Escherichia coli become restricted for methionine at 44 degrees C. A mutant strain (RG62 metK) in which the level of S-adenosylmethionine synthetase activity is only 10 to 20% of normal shows constitutive expression of one of the heat shock proteins, the lysU gene product, lysyl-tRNA synthetase form II, at 37 degrees C. These findings suggested a possible linkage between methionine metabolism and heat shock. We examined the induction of heat shock polypeptides in strain RG62 (metK) and in its parent, RG (metK+), from which it was derived by spontaneous mutation. Exponential-phase cultures of the two strains were pulse-labeled with [3H]leucine shortly after a shift from 37 to 44 degrees C, and the total cellular polypeptides were examined by two-dimensional electrophoresis. The results confirmed the constitutive production of the lysU gene product previously reported for strain RG62, but also revealed that the induction of 2 of the 17 heat shock polypeptides, C14.7 and G13.5, was markedly depressed. Otherwise the heat shock induction pattern was similar in timing and magnitude in the two strains. Transformation of the mutant strain with a plasmid, pK8, containing the metK coding sequence and promoter region as a 1.8-kilobase insert into pBR322 restored normal induction of C14.7 and G13.5, but did not prevent constitutive expression of the lysU gene product in the medium required for growth of this strain. The three heat shock polypeptides abnormally controlled in strain RG62 are the three polypeptides which are not induced when rapid synthesis of the htpR gene product is induced by isopropyl-beta-D-thiogalactopyranoside at 28 degree C (R. A. VanBogelen, M. A. Acton, and F. C. Neidhardt, Genes Dev. 1:525-531, 1987). We postulate that induction of these three polypeptides involves metabolic signals in addition to the synthesis of the htpR gene product and that strain RG62 (metK) fails to produce the signals involved in induction of C14.7 and G13.5 on a shift-up in temperature and produces the signal related to lysU induction even at 37 degree C.