Organization of Zur-dependent promoters for znuC , znuA and ykgM. The DNA sequences derived from the genomic data of Y. pestis CO92 and the start codon (ATG) of each gene was shown at the 3' terminus. The bent arrows indicated the transcription start sites and the corresponding nucleotide numbers were shown by taking the transcription start site as "+1". The predicted promoter -10 and/or -35 elements were boxed. Zur binding sites were underlined. The invert repeats in the Zur box was showed with two invert arrows.