Selvaraj G, Iyer V N
Mol Gen Genet. 1980;178(3):561-6. doi: 10.1007/BF00337861.
Evidence is presented that bacteriophage P7 specifies an analog of the E. coli DNA replication protein, dnaB. As in the related bacteriophage P1 (D'Ari et al., 1975; Ogawa, 1975), in lysogens of P7, the production of the analog protein is repressed and constitutive mutants could be isolated. Such constitutive mutants could suppress efficiently the thermosensitivity of several dnaB(ts) mutations and also rescue a strain carrying a dnaB amber mutation. While neither P7 nor the mutant P1bacban (defective in the structural gene ban) could suppress dnaB(ts) mutations efficiently, recombinants between these two phages could do so, indicating the presence of a functional dnaB analog gene (called sdb) on P7. In a dnaB amber strain suppressed by the presence of the constitutive mutant P7csb, bacteriophage lambda failed to replicate which is a further similarity between P7 and P1. P7csb mutants or P7-P1bacban recombinants were found to be less thermoresistant than P1bac1 suggesting that the P7-specified dnaB analog protein or its production is relatively less tolerant of temperatures above 37 degrees C.
有证据表明，噬菌体P7可编码大肠杆菌DNA复制蛋白dnaB的类似物。与相关噬菌体P1（D'Ari等人，1975年；小川，1975年）一样，在P7的溶原菌中，类似蛋白的产生受到抑制，并且可以分离出组成型突变体。这种组成型突变体可以有效地抑制几种dnaB（ts）突变的温度敏感性，还能拯救携带dnaB琥珀突变的菌株。虽然P7和突变型P1bacban（结构基因ban有缺陷）都不能有效地抑制dnaB（ts）突变，但这两种噬菌体之间的重组体却可以，这表明P7上存在一个功能性的dnaB类似基因（称为sdb）。在被组成型突变体P7csb抑制的dnaB琥珀菌株中，噬菌体λ无法复制，这是P7和P1之间的另一个相似之处。发现P7csb突变体或P7-P1bacban重组体比P1bac1的耐热性更低，这表明P7编码的dnaB类似蛋白或其产生对高于37摄氏度的温度相对不那么耐受。
