Comparative studies on the regulation of tryptophan synthesis.

In vitro DNA recombination techniques have revolutionized the study of genetic control of biosynthetic pathways. Using examples drawn from the pathway of tryptophan synthesis, approaches to the deciphering of regulatory signals and response mechanisms through transposition of DNA segments and DNA sequence analysis will be presented. After reviewing the known chromosomal arrangements and regulatory patterns of trp genes in the bacterial groups studied so far, and describing the results of transferring all or part of the pathway's genes from one organism to a distantly related one, the use of this technique to analyze new organisms will be described. Along with some advantages over the conventional methods there are some pitfalls. Finally, since it is likely that events analogous to recombinant DNA experiments take place readily in nature, their consequences in studies of bacterial evolution will be conjectured.