Structural Analysis of a Novel Class of R-M Controller Proteins: C.Csp231I from Citrobacter sp. RFL231.McGeehan, J.E., Streeter, S.D., Thresh, S.J., Taylor, J.E., Shevtsov, M.B., Kneale, G.G.
(2011) J.Mol.Biol. 409: 177-188
- PubMed: 21440553
- DOI: 10.1016/j.jmb.2011.03.033
- Primary Citation of Related Structures:  3LIS
- PubMed Abstract:
Controller proteins play a key role in the temporal regulation of gene expression in bacterial restriction-modification (R-M) systems and are important mediators of horizontal gene transfer. They form the basis of a highly cooperative, concentration- ...
Controller proteins play a key role in the temporal regulation of gene expression in bacterial restriction-modification (R-M) systems and are important mediators of horizontal gene transfer. They form the basis of a highly cooperative, concentration-dependent genetic switch involved in both activation and repression of R-M genes. Here we present biophysical, biochemical, and high-resolution structural analysis of a novel class of controller proteins, exemplified by C.Csp231I. In contrast to all previously solved C-protein structures, each protein subunit has two extra helices at the C-terminus, which play a large part in maintaining the dimer interface. The DNA binding site of the protein is also novel, having largely AAAA tracts between the palindromic recognition half-sites, suggesting tight bending of the DNA. The protein structure shows an unusual positively charged surface that could form the basis for wrapping the DNA completely around the C-protein dimer.
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