Redox-dependent shift of OxyR-DNA contacts along an extended DNA-binding site: a mechanism for differential promoter selection.

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作者：

MB Toledano，I Kullik，F Trinh，PT Baird，G Storz

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摘要：

The redox-sensitive protein activates the of defense genes in and represses its own expression under both oxidizing and reducing conditions. Previous studies showed that -sites are unusually long with limited sequence similarity. Here, we report that oxidized recognizes a motif comprised of four ATAGnt elements spaced at 10 bp intervals and contacts these elements in four adjacent major grooves on one face of the DNA helix. In contrast, reduced contacts two pairs of adjacent major grooves separated by one helical turn. The two modes of are essential for to function as both an activator and a repressor in vivo. We propose that specific DNA recognition by an tetramer is achieved with four contacts of intermediate affinity allowing to reposition its DNA contacts and target alternate sets of promoters as the cellular redox state is altered.

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关键词：

Oxidoreductases Peroxidases beta-Galactosidase Transcription Factors Repressor Proteins Oligodeoxyribonucleotides DNA, Bacterial Bacterial Proteins DNA-Binding Proteins Recombinant Fusion Proteins