Recognition of Dna Sequences by the Repressor and Cro Proteins of Bacteriophage 434

The discovery of regulator and operator genes, summarized and organized into a model for repressive regulation by Jacob and Monod 1r1 in il6t, defined a fundamental logical circuitry for control of gene expreision. thai celebrated formulation is surely one of the great achievements of the first century of the Institut Pasteur. chemical entities that execute this logic, the repressors and operators of lac l2l and lambda [3], were isolated and characterized in the 2 decades that followed the Jaco6 and Monod article. only one small part of their model needed revision, the repressors turned out to be proteins and not (as they had suggested) RNA. The eiegant characterization of the repressor and cro proteins of lambda and related temperate bacteriophages, and of the operator sites with which these proteins interact, revealed the dynamics of a < genetic switch ) [4].