FIG. 9.

(A) Primer extension analysis of 5′ termini of pilT-pilU transcripts. RNA was isolated from strain N400 or GT7 after 5 h of culture in Gc liquid medium. Primer extension reaction mixtures were loaded alongside DNA sequencing reaction mixtures obtained by using wild-type genomic DNA templates with the extension primers. The letters above lanes G, A, T, and C (DNA sequencing reactions) indicate the dideoxynucleotides used to terminate the reactions. The nucleotide sequences surrounding the primer extension products have been expanded. The asterisks indicate nucleotides corresponding to the start points. (B) Nucleotide sequence of the upstream region of the pilT gene. Nucleotide sequences expanded in panel A are indicated by boldface type, and the transcriptional start sites mapped by primer extension analysis are indicated by asterisks. The arrow indicates the major pilT transcriptional start site. The consensus −10 and −35 hexamers, putative ribosome binding site for pilT (RBS), and translation start site are marked. The arrowheads show transposon insertion sites in mutant strains tested or discussed in the text. The solid arrowheads indicate a conferred pilT mutant phenotype, whereas the open arrowhead indicates that the transposon insertion had no effect.