Nag D K, Chattopadhyay D J, Mandal N C
Mol Gen Genet. 1984;194(3):373-6. doi: 10.1007/BF00425547.
By mutagenizing a lambda cIts (lambda cI857) lysogen, a lambda mutant has been isolated with a wild-type phenotype. This mutant phage lysogenizes with low efficiency and produces a low burst. Though the initial rates of repressor synthesis in Escherichia coli after infection with wild-type and mutant lambda are the same, the maximum level of repressor that is synthesized in the latter case is only about 30% of that synthesized in the former. Virulent lambda plates on the lysogen of mutant lambda with slightly less efficiency producing very tiny plaques. Operator-binding studies made in vitro with purified mutant and wild-type repressors show that the binding curve of the former repressor is a rectangular hyperbola while that of the latter is sigmoid. The half-lives of the complexes of mutant and wild-type repressors with right operator are 133 and 27 min, respectively. All these results suggest that the mutant repressor possibly has a higher affinity for the operators. This mutant has been named lambda cIha (ha = high affinity).
通过对λ cIts（λ cI857）溶原菌进行诱变，分离出了一种具有野生型表型的λ突变体。这种突变噬菌体的溶原化效率低，且产生的爆发量少。虽然野生型和突变型λ感染大肠杆菌后阻遏物合成的初始速率相同，但在后一种情况下合成的阻遏物最大水平仅约为前一种情况的30%。烈性λ在突变型λ的溶原菌上形成噬菌斑的效率略低，产生的噬菌斑非常小。用纯化的突变型和野生型阻遏物进行的体外操纵子结合研究表明，前一种阻遏物的结合曲线是矩形双曲线，而后者的是S形。突变型和野生型阻遏物与右操纵子复合物的半衰期分别为133分钟和27分钟。所有这些结果表明，突变型阻遏物可能对操纵子具有更高的亲和力。这个突变体被命名为λ cIha（ha = 高亲和力）。
