DNA binding ability of the Nse1-Nse3-Nse4 sub-complex is critical for essential function of the SMC5-6 complex
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| Year of publication | 2013 |
| Type | Conference abstract |
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| Description | Smc5-6 is a highly conserved protein complex related to cohesin and condensin involved in the structural maintenance of chromosomes. The Smc5-6 complex is essential for proliferation in yeast and is involved in the homologous recombination-based DNA repair processes, including repair of DNA double strand breaks, restart of stalled replication forks etc. However, the precise mechanism of SMC5-6 function is not known. We will present the evidence for direct physical interaction of its part, Nse1-Nse3-Nse4 sub-complex, to DNA and its essential role for the function of the whole SMC5-6 complex. The Nse1-Nse3-Nse4 sub-complex is rich in winged-helix domain motifs and at least two of them form a putative DNA-binding cleft. Indeed, purified Nse1-Nse3-Nse4 sub-complexes shift different DNA substrates in electromobility shift assays proving their ability to bind DNA. Mutations of the key basic residues within the putative DNA-binding cleft result in significantly lower affinity to DNA compared to the wild-type sub-complexes suggesting that the proposed cleft mediates specific interactions with DNA substrates. Introduction of these mutations into S. pombe genome results in cell death and/or hypersensitivity to hydroxyurea. The lethal phenotype indicates that the interaction of the cleft with DNA is crucial for the essential function of the SMC5-6 complex. |
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