Comparison of the E. coli and Y. pestis gcvA/gcvB control regions and gcvB genes. Ec, E. coli; Yp, Y. pestis. Bases that are identical are boxed in gray. The E. coli promoter -10 and -35 sequences are underlined for gcvA  and overlined for gcvB . Arrows indicate transcription start sites and directions of transcription of gcvA and gcvB. The GcvA binding region is indicated above the sequence . The deduced Y. pestis -10 and -35 promoter sequences are underlined for gcvA and overlined for gcvB, and the deduced GcvA binding site is indicated above the sequence. Two Rho-independent transcription terminators for the E. coli and Y. pestis gcvB genes are indicated by inverted arrows. The fusion points for transcriptional fusions gcvB+53::lacZ (TF-1), gcvB+164::lacZ (TF-2) and gcvB+251::lacZ (TF-3) are indicated by vertical arrows.