FIG. 3.

DNase I footprinting assays. All DNA fragments were 3′ end labeled with [α-³²P]dCTP on one strand and were incubated in the presence of Co²⁺ (300 μM) and DtxR (1000 nM for pIRP3 and its variants; 200 nM for pIRP1 and its variant). (A) Lanes: 1, pIRP1 with no DtxR; 2, pIRP1 with DtxR; 3, pIRP1 T(+7)C with DtxR. (B) Lanes: 1, pIRP3 with no DtxR; 2, pIRP3 with DtxR; 3, pIRP3 C(+7)T with DtxR; 4, pIRP3 C(+7)T/A(−7)G with DtxR. Brackets indicate sequences protected by DtxR from DNase I digestion.