TABLE 3.

Putative iron binding sequences in the promoter regions of fxbA, orf1, fxuC, and fxuD genes

Site or gene	Sequencea
Consensus DtxR-binding siteb	TTAGGTTAGCCTAACCTAA
fxbA	AAAGGTAAGGCTTACCAAT
orf1	ATTGGTAAGCCTTACCTTT
fxuC	AGGTTCGACTCCGAGACCT
fxuD	GACCAGGTACTCACCGGGT

^aThe bold letters indicate the strictly conserved nucleotides; the remaining letters are the nonconserved nucleotides. 

^bThe 19-bp DtxR-binding consensus sequence of C. diphtheriae (37, 44).