Db. Garrity et Sa. Zahler, MUTATIONS IN THE GENE FOR A TRANSFER-RNA THAT FUNCTIONS AS A REGULATOR OF A TRANSCRIPTIONAL ATTENUATOR IN BACILLUS-SUBTILIS, Genetics, 137(3), 1994, pp. 627-636
It has been proposed that uncharged tRNA molecules may act as positive
regulatory factors to control the expression of a number of operons i
n Bacillus subtilis and related bacteria by interacting with leader se
quences to cause antitermination. In this study we report the isolatio
n and characterization of regulatory mutations that modify one of the
tRNA molecules predicted to have such a regulatory role. Three differe
nt alleles of the B. subtilis leucine tRNA gene leu G were found that
resulted in higher expression of the ilv-leu biosynthetic operon. Each
resulted in a base change in the D-loop of the leucine tRP\JA molecul
e with the anticodon 5'-GAG-3' (leucine tRNA(GAG)). Experiments with s
trains that are diploid for mutant and wild-type alleles suggested tha
t both charged and uncharged tRNA molecules may interact with leader s
equences to control expression of the operon.