Mogk A, Bukau B, Lutz R, Schumann W
Institute of Genetics, University of Bayreuth, D-95440 Bayreuth, Germany.
J Bacteriol. 1999 Mar;181(6):1971-4. doi: 10.1128/JB.181.6.1971-1974.1999.
The highly conserved DnaK chaperones consist of an N-terminal ATPase domain, a central substrate-binding domain, and a C-terminal domain whose function is not known. Since Bacillus subtilis dnaK was not able to complement an Escherichia coli dnaK null mutant, we performed domain element swap experiments to identify the regions responsible for this finding. It turned out that the B. subtilis DnaK protein needed approximately normal amounts of the cochaperone DnaJ to be functional in E. coli. The ATPase domain and the substrate-binding domain form a species-specific functional unit, while the C-terminal domains, although less conserved, are exchangeable. Deletion of the C-terminal domain in E. coli DnaK affected neither complementation of growth at high temperatures nor propagation of phage lambda but abolished degradation of sigma32.
高度保守的DnaK伴侣蛋白由一个N端ATP酶结构域、一个中央底物结合结构域和一个功能未知的C端结构域组成。由于枯草芽孢杆菌的dnaK不能互补大肠杆菌的dnaK缺失突变体，我们进行了结构域元件交换实验，以确定导致这一结果的区域。结果表明，枯草芽孢杆菌的DnaK蛋白在大肠杆菌中发挥功能需要大致正常量的共伴侣蛋白DnaJ。ATP酶结构域和底物结合结构域形成一个物种特异性的功能单元，而C端结构域虽然保守性较低，但可相互交换。在大肠杆菌DnaK中缺失C端结构域既不影响高温下生长的互补，也不影响λ噬菌体的繁殖，但消除了σ32的降解。
