GENETIC CONTROL OF ENZYME STRUCTURE 19 



mutationally altered gene to elicit the formation of a functional 

 tryptophan synthetase. 



Conclusion 



The studies summarized in this paper indicate that genetic in- 

 formation, contained witliin a restricted region which controls the 

 formation of the enzxme Tsase, is subject to considerable modifica- 

 tion. These modifications result in specific alterations in the prop- 

 erties of tryptophan synthetase. These are being examined at both 

 the protein and the amino acid leyel. Furthermore, the types of 

 specific structural modifications in the protein, observed following 

 mutation, can be correlated with damage to yery specific regions 

 within the total genetic area which controls tryptophan synthetase 

 formation. These regions also show yery specific types of intergenic 

 and intra uenic interaction. 



Perhaps this paper can best be concluded by framing several 

 questions. For example, do changes other than changes in the pri- 

 mary structure of a protein occur as a result of mutation? Are 

 CRM-less mutations really mutations of the "non-sense" type? What 

 explanations exist at the molecular level for suppressor action, partial 

 and true reversion, and complementation? And finally, can these 

 mutant systems provide clues to the relationship of the DNA code 

 to protein structure? Certainly approaches are now available which 

 may provide answers to most of these questions in the near future. 



References 



Beadle, G. W. 1959. Genes and chemical reactions in Neurospora. Science 129: 



1715-1719. 

 Benzeh, S. 1957. The elementary units of heredity. In The Chemical Basis of 



Heredity, eds. W. D. McElroy and B. Glass. Johns Hopkins University Press, 



Baltimore. Pp. 70-93. 

 Benzer, S., and E. Freese. 1958. Induction of specific mutation with 5-bromouracil. 



Proc. Natl. Acad. Sci. U.S. 44: 112-119. 

 Bonner, D. M. 1959. Gene action. In Thirteenth Annual Symposium on Cancer 



Research. \i. D. Anderson Memorial Hospital, Houston, Texas. 

 Bonner, D. M., Y. Suvama, and J. A. De Moss. 1960. Genetic fine structure and 



enzyme fonnation. Federation Proc. 19: 926-930. 

 Carsiotis, M., D. S. Ligon, and S. R. Suskind. 1960. Unpublished results. 

 Crawford, 1. P., and C. Yanofsky, 1958. On the separation of the tryptophan 



synthetase of Escherichia coli into two protein components. Proc. Natl. Acad. Sci. 



U.S. 44: 1161-1170. 

 Crick, F. H. C. 1958. On protein synthesis. Sympos. Soc. Exptl. Biol. 12: 138-163. 

 Crick, F. H. C. 1959. The present position of the coding problem. Brookhaven 



Symposia in Biol. 12: 35-39. 



