A RE COMBINATION FUNCTION ESSENTIAL TO THE GROWTH OF BACTERIO PHAGE P-22
A RE COMBINATION FUNCTION ESSENTIAL TO THE GROWTH OF BACTERIO PHAGE P-22
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DOI：
10.1016/0022-2836(70)90119-1
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发表时间：
1970-01-01
影响因子：
5.6
通讯作者：
MATZ M J
中科院分区：
文献类型：
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作者：
BOTSTEIN D;MATZ M J
沙门氏菌噬菌体P22的突变体已经被分离出来，它们在感染重组缺陷（rec−）宿主后不能生长。这些突变体（命名为f-foresentialrecombinationfunction）在噬菌体特异性重组系统中有缺陷，如在rec+和rec-宿主中进行的两因子和三因子杂交所示。详细研究的Fourerf−突变体属于一个互补组;erf+对erf −是显性的。f基因位于噬菌体遗传图谱的“早期”区域。f −突变体在感染rec −宿主后的表型包括不能生长、不能溶原化和不能维持噬菌体DNA合成超过大约一轮复制。晚期噬菌体功能似乎在erf −突变体中正常表达，感染的环状排列的、末端重复的噬菌体DNA的环化似乎是重组所需的基本步骤。这一观点得到了以下观察结果的支持：在溶原菌诱导后，anerf−噬菌体可以在rec −细胞质中正常生长;在这种情况下，DNA可能是通过原噬菌体切除机制环化的。我们得出结论，重组对于生长是必不可少的，因为线性感染DNA必须通过重组环化。在没有重组的情况下不能维持DNA合成表明，环化对于噬菌体基因组的成功复制是拓扑学上必不可少的。
Mutants of theSalmonellaphage P22 have been isolated which cannot grow after infection of recombination-deficient (rec−) hosts. These mutants (designatederf−foressentialrecombinationfunction) are defective in a phage-specified recombination system, as shown by two and three-factor crosses carried out inrec+andrec−hosts. Fourerf−mutants examined in detail fall into one complementation group;erf+is dominant toerf−. Theerfgene is located in the “early” region of the phage genetic map.The phenotype oferf−mutants after infection ofrec−hosts includes failure to grow, to lysogenize, and to sustain phage DNA synthesis beyond about one round of replication. Late phage functions appear to be expressed normally byerf−mutants.Circularization of the infecting circularly permuted, terminally repetitious phage DNA seems to be the essential step for which recombination is required. This idea is supported by the observation that anerf−phage can grow normally inrec−cytoplasm after induction of a lysogen; in this case the DNA is presumably circularized by the prophage excision mechanism.We conclude that recombination is essential to growth because the linear infecting DNA must be circularized by recombination. The inability to sustain DNA synthesis in the absence of recombination suggests that circularization is topologically essential to successful replication of the phage genome.