PMID:16024043
| Citation |
Kosinski, J, Steindorf, I, Bujnicki, JM, Giron-Monzon, L and Friedhoff, P (2005) Analysis of the quaternary structure of the MutL C-terminal domain. J. Mol. Biol. 351:895-909 |
|---|---|
| Abstract |
The dimeric DNA mismatch repair protein MutL has a key function in communicating mismatch recognition by MutS to downstream repair processes. Dimerization of MutL is mediated by the C-terminal domain, while activity of the protein is modulated by the ATP-dependent dimerization of the highly conserved N-terminal domain. Recently, a crystal structure analysis of the Escherichia coli MutL C-terminal dimerization domain has been reported and a model for the biological dimer was proposed. In this model, dimerization is mediated by the internal (In) subdomain comprising residues 475-569. Here, we report a computational analysis of all protein interfaces observed in the crystal structure and suggest that the biological dimer interface is formed by a hydrophobic surface patch of the external (Ex) subdomain (residues 432-474 and 570-615). Moreover, sequence analysis revealed that this surface patch is conserved among the MutL proteins. To test this hypothesis, single and double-cysteine variants of MutL were generated and tested for their ability to be cross-linked with chemical cross-linkers of various size. Finally, deletion of the C-terminal residues 605-615 abolished homodimerization. The biochemical data are fully compatible with a revised model for the biological dimer, which has important implications for understanding the heterodimerization of eukaryotic MutL homologues, modeling the MutL holoenzyme and predicting protein-protein interaction sites. |
| Links |
PubMed Online version:10.1016/j.jmb.2005.06.044 |
| Keywords |
Adenosine Triphosphatases/chemistry; Adenosine Triphosphatases/genetics; Amino Acid Sequence; Binding Sites; Conserved Sequence; Crystallography, X-Ray; Cysteine/chemistry; DNA Repair Enzymes/chemistry; DNA Repair Enzymes/genetics; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/genetics; Dimerization; Endodeoxyribonucleases/chemistry; Endodeoxyribonucleases/genetics; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Models, Molecular; Molecular Sequence Data; Protein Engineering; Protein Structure, Quaternary; Protein Structure, Tertiary; Recombinant Proteins/chemistry; Recombinant Proteins/genetics; Sequence Deletion; Sequence Homology, Amino Acid; Thermodynamics |
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