Wada M, Kano Y, Ogawa T, Okazaki T, Imamoto F
Laboratory of Molecular Genetics, (Riken) Tsukuba Life Science Center, Ibaraki, Japan.
J Mol Biol. 1988 Dec 5;204(3):581-91. doi: 10.1016/0022-2836(88)90357-9.
Insertion and deletion mutations of the hupB and hupA genes, which encode the HU-1 and HU-2 proteins, respectively, of Escherichia coli, have been constructed in vitro and transferred to the hup loci on the bacterial chromosome. The mutations were constructed by inserting a gene encoding chloramphenicol resistance or kanamycin resistance into the coding region of the hupB or hupA gene, respectively. A complete deletion of the hupA gene was constructed by replacing the entire hupA coding region with the kanamycin resistance gene. Cells in which either the hupB or the hupA gene is defective grow normally, but cells in which both of the hup genes are defective exhibit phenotypes different from the wildtype strain. The hupA-hupB double mutants are cold-sensitive, although their growth rate is normal at 37 degrees C. Furthermore, the viability of the hupA-hupB double mutants is severely reduced when the cells are subjected to either cold shock or heat shock, indicating that the hup genes are essential for cell survival under some conditions of stress. The double mutants also exhibit filamentation when grown in the lower range of permissive growth temperature.
分别编码大肠杆菌HU-1和HU-2蛋白的hupB和hupA基因的插入和缺失突变已在体外构建，并转移至细菌染色体上的hup位点。这些突变是通过分别将编码氯霉素抗性或卡那霉素抗性的基因插入hupB或hupA基因的编码区构建而成的。通过用卡那霉素抗性基因替换整个hupA编码区构建了hupA基因的完全缺失。hupB或hupA基因有缺陷的细胞生长正常，但两个hup基因都有缺陷的细胞表现出与野生型菌株不同的表型。hupA-hupB双突变体对冷敏感，尽管它们在37℃时生长速率正常。此外，当细胞受到冷休克或热休克时，hupA-hupB双突变体的活力会严重降低，这表明hup基因在某些应激条件下对细胞存活至关重要。双突变体在允许生长温度的较低范围内生长时也会出现丝状化。
