FIG. 3.

Gel retardation of a ³²P-labeled gntP promoter probe by purified UxuR. All lanes contained 8 nmol of a radioactively labeled DNA fragment containing the UxuR operator. Lane 1, no protein. Lanes 2 to 9 contain increasing amounts of UxuR: 0.9, 1.8, 3.6, 7.2, 14.4, 28.8, 57.6, and 115.2 nmol, respectively. Lanes 10 to 13 represent competition experiments using unlabeled gntP fragments: lane 10, 25×; lane 11, 100×; lane 12, 200×; and lane 13, 300× unlabeled fragment (by weight). The shifted band (b) and free DNA (a) are indicated on the left.