Structure and function of the repressor of bacteriophage lambda

✍ Scribed by Nag, D. K. ;Chattopadhyay, D. J. ;Mandal, N. C.

• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 455 KB
• Volume: 194
• Category: Article
• ISSN: 0026-8925
• DOI: 10.1007/bf00425547

✦ Synopsis

By mutagenizing a 2cIts (2ci857) lysogen, a 2 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 2 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 2 plates on the lysogen of mutant 2 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 2cIha (ha = high affinity).