Allosteric effects of SSB C-terminal tail on assembly ofE. coliRecOR proteins
| Autor: | Timothy M. Lohman, Alexander G. Kozlov, Min Kyung Shinn |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
AcademicSubjects/SCI00010
Escherichia coli Proteins Allosteric regulation Cooperative binding Plasma protein binding Hydrogen-Ion Concentration Genome Integrity Repair and Replication Biology medicine.disease_cause RecF pathway DNA-Binding Proteins chemistry.chemical_compound Allosteric Regulation chemistry Tetramer Genetics medicine Biophysics Thermodynamics Protein Multimerization Homologous recombination Escherichia coli DNA Protein Binding |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| Popis: | Escherichia coli RecO is a recombination mediator protein that functions in the RecF pathway of homologous recombination, in concert with RecR, and interacts with E. coli single stranded (ss) DNA binding (SSB) protein via the last 9 amino acids of the C-terminal tails (SSB-Ct). Structures of the E. coli RecR and RecOR complexes are unavailable; however, crystal structures from other organisms show differences in RecR oligomeric state and RecO stoichiometry. We report analytical ultracentrifugation studies of E. coli RecR assembly and its interaction with RecO for a range of solution conditions using both sedimentation velocity and equilibrium approaches. We find that RecR exists in a pH-dependent dimer-tetramer equilibrium that explains the different assembly states reported in previous studies. RecO binds with positive cooperativity to a RecR tetramer, forming both RecR4O and RecR4O2 complexes. We find no evidence of a stable RecO complex with RecR dimers. However, binding of RecO to SSB-Ct peptides elicits an allosteric effect, eliminating the positive cooperativity and shifting the equilibrium to favor a RecR4O complex. These studies suggest a mechanism for how SSB binding to RecO influences the distribution of RecOR complexes to facilitate loading of RecA onto SSB coated ssDNA to initiate homologous recombination. |
| Databáze: | OpenAIRE |
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