Fig 9.

Effect of wild-type and mutant Spx on RNAP/trxB promoter DNA cross-linking. APB-derivatized and radiolabeled trxB promoter DNA was incubated with 0.25 μM RNAP in the absence or presence of 2.5 μM Spx or mutant proteins. After UV irradiation and DNase I treatment, the cross-linking result was analyzed by SDS-PAGE, and cross-linked proteins were detected by phosphorimaging. (A) Cross-linking result at positions −36, −40, and −44 on trxB promoter. (B and C) Summary of the results of cross-linking experiment at all positions investigated. The sequence of the trxB promoter is shown in the middle, and the APB (UV-activated cross-linker)-derivatized position is labeled gray. The binding intensity of each cross-linked protein in the absence (B) and presence (C) of Spx is indicated by an asterisk. Two or three asterisks represent more binding of the specified protein detected at the position examined on the trxB promoter.