The mitochondrial single-stranded DNA binding protein from S. cerevisiae, Rim1, does not form stable homo-tetramers and binds DNA as a dimer of dimers
| Autor: | Saurabh Singh, Roberto Galletto, Edwin Antony, Paolo De Bona, Vandna Kukshal |
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| Rok vydání: | 2018 |
| Předmět: |
Models
Molecular 0301 basic medicine Saccharomyces cerevisiae Proteins Low protein Protein Conformation Dimer Saccharomyces cerevisiae DNA Single-Stranded Plasma protein binding Genome Integrity Repair and Replication Crystallography X-Ray 03 medical and health sciences chemistry.chemical_compound Protein structure Tetramer Genetics 030102 biochemistry & molecular biology biology Point mutation biology.organism_classification Mitochondria DNA-Binding Proteins Repressor Proteins 030104 developmental biology chemistry Biophysics Nucleic Acid Conformation Protein Multimerization DNA Protein Binding |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| DOI: | 10.1093/nar/gky530 |
| Popis: | Rim1 is the mitochondrial single-stranded DNA binding protein in Saccharomyces cerevisiae and functions to coordinate replication and maintenance of mtDNA. Rim1 can form homo-tetramers in solution and this species has been assumed to be solely responsible for ssDNA binding. We solved structures of tetrameric Rim1 in two crystals forms which differ in the relative orientation of the dimers within the tetramer. In testing whether the different arrangement of the dimers was due to formation of unstable tetramers, we discovered that while Rim1 forms tetramers at high protein concentration, it dissociates into a smaller oligomeric species at low protein concentrations. A single point mutation at the dimer–dimer interface generates stable dimers and provides support for a dimer–tetramer oligomerization model. The presence of Rim1 dimers in solution becomes evident in DNA binding studies using short ssDNA substrates. However, binding of the first Rim1 dimer is followed by binding of a second dimer, whose affinity depends on the length of the ssDNA. We propose a model where binding of DNA to a dimer of Rim1 induces tetramerization, modulated by the ability of the second dimer to interact with ssDNA. |
| Databáze: | OpenAIRE |
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