Publication details
Effect of amino acid substitutions in the rad50 ATP binding domain on DNA double strand break repair in yeast.
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Biological Chemistry |
| MU Faculty or unit | |
| Citation | |
| Web | http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15546877&query_hl=20&itool=pubmed_docsum |
| Field | Biochemistry |
| Keywords | Rad50; ATPase; repair; |
| Description | The Saccharomyces cerevisiae Rad50-Mre11-Xrs2 complex plays a central role in the cellular response to DNA double strand breaks. Rad50 has a globular ATPase head domain with a long coiled-coil tail. DNA binding by Rad50 is ATP-dependent and the Rad50-Mre11-Xrs2 complex possesses DNA unwinding and endonuclease activities that are regulated by ATP. Here we have examined the role of the Rad50 Walker type A ATP binding motif in DNA double strand break repair by a combination of genetic and biochemical approaches. Replacement of the conserved lysine residue within the Walker A motif with alanine, glutamate, or arginine results in the same DNA damage sensitivity and homologous recombination defect as the rad50 deletion mutation. The Walker A mutations also cause a deficiency in non-homologous end-joining. As expected, complexes containing the rad50 Walker A mutant proteins are defective in ATPase, ATP-dependent DNA unwinding, and ATP-stimulated endonuclease activities. Although the DNA end-bridging activity of the Rad50-Mre11-Xrs2 complex is ATP-independent, the end-bridging activity of complexes containing the rad50 Walker A mutant proteins is salt-sensitive. These results provide a molecular explanation for the observed in vivo defects of the rad50 Walker mutant strains and reveal a novel ATP-independent function for Rad50 in DNA end-bridging. |