组成型整合酶合成的意义。
Significance of constitutive integrase synthesis.
作者信息
Campbell A
出版信息
Proc Natl Acad Sci U S A. 1976 Mar;73(3):887-90. doi: 10.1073/pnas.73.3.887.
One conceivable function for constitutive integrase formation by lambda prophage is to stabilize the inserted state by catalyzing reinsertion of prophages that are accidentally excised. As this hypothesis implies a dynamic equilibrium betwen inserted and noninserted DNA, the existence of such an equilibrium is explored. By examining the frequency with which prophages appear in an initially unoccupied chromosomal site of a lysogenic bacterium in which the prophage attachment site is duplicated, the off-rate is estimated as less than 10(-2) per generation for wild-type lambda, and less than 4 x 10(-4) for N- mutants of lambda. From the rate of integrase-catalyzed haploidization of certain partial diploid strains, the rate of spontaneous integrase activity is estimated as 3 x 10(-3) per generation. From these values I conclude that constitutive integrase will not appreciably stabilize the inserted state by virtue of its known activity.
λ原噬菌体组成型整合酶形成的一个可能功能是通过催化意外切除的原噬菌体重新插入来稳定插入状态。由于该假说暗示了插入和未插入DNA之间的动态平衡，因此对这种平衡的存在进行了探索。通过检查原噬菌体出现在溶原性细菌最初未被占据的染色体位点（其中原噬菌体附着位点被复制）的频率，野生型λ的解离速率估计为每代小于10^(-2)，λ的N-突变体小于4×10^(-4)。根据某些部分二倍体菌株整合酶催化单倍体化的速率，自发整合酶活性的速率估计为每代3×10^(-3)。根据这些值，我得出结论，组成型整合酶不会因其已知活性而显著稳定插入状态。
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