Structural analysis of the genetic switch that regulates the expression of restriction-modification genes.

ABSTRACT: Controller (C) proteins regulate the timing of the expression of restriction and modification (R-M) genes through a combination of positive and negative feedback circuits. A single dimer bound to the operator switches on transcription of the C-gene and the endonuclease gene; at higher concentrations, a second dimer bound adjacently switches off these genes. Here we report the first structure of a C protein-DNA operator complex, consisting of two C protein dimers bound to the native 35 bp operator sequence of the R-M system Esp1396I. The structure reveals a role for both direct and indirect DNA sequence recognition. The structure of the DNA in the complex is highly distorted, with severe compression of the minor groove resulting in a 50 degrees bend within each operator site, together with

SUBMITTER: McGeehan JE 

PROVIDER: S-EPMC2504287 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature