PMID:20639540
| Citation |
Massad, T, Skaar, K, Nilsson, H, Damberg, P, Henriksson-Peltola, P, Haggård-Ljungquist, E, Högbom, M and Stenmark, P (2010) Crystal structure of the P2 C-repressor: a binder of non-palindromic direct DNA repeats. Nucleic Acids Res. 38:7778-90 |
|---|---|
| Abstract |
As opposed to the vast majority of prokaryotic repressors, the immunity repressor of temperate Escherichia coli phage P2 (C) recognizes non-palindromic direct repeats of DNA rather than inverted repeats. We have determined the crystal structure of P2 C at 1.8 Å. This constitutes the first structure solved from the family of C proteins from P2-like bacteriophages. The structure reveals that the P2 C protein forms a symmetric dimer oriented to bind the major groove of two consecutive turns of the DNA. Surprisingly, P2 C has great similarities to binders of palindromic sequences. Nevertheless, the two identical DNA-binding helixes of the symmetric P2 C dimer have to bind different DNA sequences. Helix 3 is identified as the DNA-recognition motif in P2 C by alanine scanning and the importance for the individual residues in DNA recognition is defined. A truncation mutant shows that the disordered C-terminus is dispensable for repressor function. The short distance between the DNA-binding helices together with a possible interaction between two P2 C dimers are proposed to be responsible for extensive bending of the DNA. The structure provides insight into the mechanisms behind the mutants of P2 C causing dimer disruption, temperature sensitivity and insensitivity to the P4 antirepressor. |
| Links |
PubMed PMC2995052 Online version:10.1093/nar/gkq626 |
| Keywords |
Alanine/chemistry; Amino Acid Sequence; Bacteriophage P2/physiology; Base Sequence; Binding Sites; Crystallography; DNA/chemistry; Dimerization; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Operator Regions, Genetic; Protein Binding; Repetitive Sequences, Nucleic Acid; Sequence Deletion; Viral Proteins/chemistry; Viral Proteins/genetics; Viral Proteins/metabolism |
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