FIG. 1.

Identification of an Mga-regulated transcriptional start site for sof-sfbX. (A) Sequence of sof-sfbX promoter region from serotype M22 indicating the transcriptional start site (asterisk and black arrow), −10 and −35 regions (solid bars), the putative Mga-binding site (darkened box), and the sof start of translation (gray arrow). The sequence is numbered using the Psof-sfbX transcriptional start site as +1. (B) Primer extension analysis was performed on total RNA isolated from serotype M22 AL168str-r (Mga⁺) and nr4 (Mga⁻) using the radiolabeled antisense primer Psof-R1 (Table 2) as described in Materials and Methods. The start of transcription for sof-sfbX (asterisk) and its corresponding −10 hexamer are shown.