Hupp T R, Keasling J D, Cooper S, Kaguni J M
Department of Microbiology and Immunology, University of Michigan, Ann Arbor 48109-0620.
Res Microbiol. 1994 Feb;145(2):99-109. doi: 10.1016/0923-2508(94)90003-5.
DnaK protein is involved in the initiation of DNA synthesis from the Escherichia coli chromosome as well as from the replication origins of phage lambda and P1. The synthesis of dnaK mRNA and protein has been reported to vary during the cell cycle of Caulobacter crescentus (Gomes et al., 1990). We have measured the expression of DnaK protein during the E. coli division cycle using the membrane-elution method. Cells labelled with a radioactive amino acid at different times during the division cycle were analysed for radiolabelled DnaK protein by quantitative immunoprecipitation, gel electrophoresis and autoradiography. In contrast to reports of cell-cycle-specific synthesis of DnaK protein in C. crescentus, we find the synthesis of DnaK protein to be invariant during the E. coli division cycle. Its synthesis occurs exponentially, as does the synthesis of total cell protein.
DnaK蛋白参与大肠杆菌染色体以及噬菌体λ和P1复制起点的DNA合成起始过程。据报道，新月柄杆菌细胞周期中dnaK mRNA和蛋白的合成会发生变化（戈麦斯等人，1990年）。我们使用膜洗脱法测量了大肠杆菌分裂周期中DnaK蛋白的表达。通过定量免疫沉淀、凝胶电泳和放射自显影分析在分裂周期不同时间用放射性氨基酸标记的细胞中的放射性标记DnaK蛋白。与新月柄杆菌中DnaK蛋白细胞周期特异性合成的报道相反，我们发现大肠杆菌分裂周期中DnaK蛋白的合成是不变的。其合成呈指数增长，总细胞蛋白的合成也是如此。
