Abstract
The 5'' non-coding region of the tyrosyl-tRNA synthetase gene (tyrS) of Bacillus stearothermophilus is 324 nucleotides long. It contains a premature terminator and a strong promoter: these were identified in vitro by RNA run-off experiments and in Escherichia coli by construction of specific mutants. The terminator consists of a stem and loop structure followed by the string of T residues characteristic of rho-independent termination. This is preceded by another stem and loop structure which may permit the formation of an anti-terminator. Neither the promoter nor the premature terminator appears to be regulated by the tyrosyl-tRNA synthetase in vitro or in E. coli.