2 



Control by Repression 



Henry J. Vogel ^ 



Among the mechanisms controlhng celhilar function, there are 

 two, namely repression and induction, that represent effects of spe- 

 cific small molecules on the synthesis of enzymes and possibly other 

 proteins. These two mechanisms complement each other and, in 

 various ways, have curiously intertwined histories. About sixty years 

 ago, Dienert (1900) described phenomena that presumably reflect 

 enzyme induction, and he also reported an apparent antagonism to 

 enzyme formation that suggests enzyme repression. Our interest in 

 this area stems from an experiment (Vogel and Davis, 1952) that 

 was intended to bear on the possibility that even "constitutive" en- 

 zymes, such as those of arginine synthesis, require induction for their 

 formation. The results then obtained seemed to be compatible with 

 this notion; further work, however, pointed to a different explana- 

 tion and led to the finding that arginine added to growing cultures 

 of a strain of Escherichia coli represses the formation of acetyl- 

 ornithinase (Vogel, 1953a). This enzyme catalyzes a step in the 

 arginine pathway, namely the conversion of acetylornithine to orni- 

 thine (Vogel, 1952; Vogel and Bonner, 1956). Interestingly enough, 

 a number of other early instances of repression were discovered al- 

 most simultaneously in several laboratories (Table 2-1), among 

 them, the antagonism of galactose to the synthesis of yS-galactosidase 



1 Institute of Microbiology, Rutgers, The State Uni\ersity, New Brunswick, New 

 Jersey. Work from the author's laboratory was aided by grants from the Damon 

 Runyon Memorial Fund and the United States Public Health Service and by a contract 

 between the Office of Naval Research, Department of the Navy, and Rutgers, The 

 State University. 



23 



