Kadowaki K, Shibata T, Takeuchi K, Himeno M, Sakai H, Komano T
Department of Agricultural Chemistry, Kyoto University, Japan.
J Gen Virol. 1987 Sep;68 ( Pt 9):2443-7. doi: 10.1099/0022-1317-68-9-2443.
Bacteriophage phi X174am3trD, a high temperature-resistant mutant of phi X174am3, was 10(4) times more stable than phi X174am3 as judged by its survival ratio after heat treatment at 54 degrees C for 120 min. Complementation tests showed an involvement of gene G. Sequence analysis of this gene revealed three mutation sites, one transition and two insertions. The first was a silent mutation and the others brought about a change in one amino acid and an addition of another, respectively, in the gene G protein. These changes in amino acid sequence resulted in a change in the secondary structure of the protein. A beta-turn region in part of the gene G protein of phi X174am3 was changed to an alpha-helix in phi X174am3trD. These results indicate that the temperature resistance of phi X174am3trD may be caused by elevated hydrophobicity in the mutated region or by strong interaction between the mutated gene G protein and other capsid proteins.
噬菌体φX174am3trD是φX174am3的一种耐高温突变体，通过在54℃热处理120分钟后的存活率判断，其稳定性比φX174am3高10^4倍。互补试验表明基因G参与其中。对该基因的序列分析揭示了三个突变位点，一个转换和两个插入。第一个是沉默突变，其他两个分别导致基因G蛋白中的一个氨基酸发生变化和另一个氨基酸的添加。氨基酸序列的这些变化导致了蛋白质二级结构的改变。φX174am3的基因G蛋白部分中的一个β-转角区域在φX174am3trD中变成了α-螺旋。这些结果表明，φX174am3trD的耐热性可能是由突变区域疏水性的提高或突变的基因G蛋白与其他衣壳蛋白之间的强相互作用引起的。
