FIG. 1.

Nucleotide sequence at the 5′ end of the B. subtilis pyrG 5′ untranslated leader RNA. DNA specifying the pyrG promoter and this leader RNA was fused to lacZ for the studies of pyrG expression in this work. Three RNA sequences found to be conserved in the pyrG leader sequences of several gram-positive bacteria (8) are shown in boldface. The computer program MFOLD (7, 15) predicts the secondary structure shown. The transcription terminator stem-loop following nucleotide +38 was previously shown to be essential for repression of pyrG expression by cytidine (8). Numbering of the sequence is based on the G nucleotide at +1 as the probable start site of transcription (see the text).