FIG 5.

Fur protects GATC-32 from methylation in vitro and in vivo. (A) A radiolabeled PCR product corresponding to the 570-bp P₄₅₃₂ fragment was digested by the restriction enzymes indicated on top. Left panel, untreated PCR product; middle panel, PCR product treated with the Dam methylase; right panel, PCR product incubated with purified Fur (20 nM) prior to Dam methylation. Molecular weight markers (in base pairs) are indicated on the left. The sizes of the digestion products (in base pairs) are indicated on the right. See Fig. S2 in the supplemental material for positions of restriction sites and sizes of expected DNA fragments. (B) The P₄₅₃₂ promoters isolated from pGE573 vectors carrying the P₄₅₃₂-lacZ fusion purified from the EAEC wild-type strain (WT) or its isogenic dam or fur mutant strain or from the WT strain treated with 2,2’-dipyridyl were digested by the restriction enzymes indicated on top. Molecular weight markers (in base pairs) are indicated on the left. The sizes of the digestion products (in base pairs) are indicated on the right. The dashed lines indicate reorganization of the lanes from the same gel. See Fig. S2 for positions of restriction sites and sizes of expected DNA fragments.