A Biochemical and Genetic Study of Reversion With the a-Gene a-Protein System of Escherichia Coli Tryptophan Synthetase

Abstract

TRAINS which approach wild type in behavior can arise from mutant strains a result of either reversion (mutation of the gene altered by the original mutation), or suppression (mutation of some other gene). Recently it has become evident that reversion is an exceedingly complex phenomenon, whether analyzed at the level of genetic fine structure or in terms of modifications of specific proteins. Reversion may not only occur at the same site as the original mutational alteration but at other sites within the same gene (JINKS 1961;CRICK, BARNETT, BRENNER and WATTS-TOBIN 1961 ; YANOFSKY, HELINSKI and MALING 1961 ; HELINSKI and YANOFSKY 1963). The specific enzyme activities that are restored by reversion may be associated with proteins resembling the wild-type protein, or with proteins that are clearly different (MAAS and DAVIS

Temperature-sensitive revertants

“…In this paper the term 'revertant' means phenotypic revertant and includes apparent full revertants and partial revertants , and it could also include suppressor mutations (Allen and Yanofsky, 1963). The effect of mutagens has not yet been tested in the selection of tS revertants.…”