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Reports

Non-Catalytic Function for ATR in the Checkpoint Response

Troy D. McSherry, Ana A. Kitazono, Ali Javaheri, Stephen J. Kron and Paul Mueller

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The ATR family of checkpoint kinases is essential for an appropriate response to genomic insults in eukaryotes. Included in this family are Mei-41 in Drosophila, Mec1 in S. cerevisiae, Rad3 in S. pombe, and ATR in vertebrates. These large kinases phosphorylate and modify multiple cell cycle and checkpoint factors, leading to cell cycle arrest, DNA repair, and induction of apoptosis. The catalytic domain of all ATR family members comprises only a fraction of the total protein. Here, we show that the non-catalytic portion of ATR has a conserved function in the checkpoint response. Expression of either wild type or various kinase defective forms of Xenopus ATR (XATR) in S. cerevisiae mec1 mutants suppresses the checkpoint defect and induces a DNA damage dependent mitotic cell cycle arrest. This suppression requires the presence of yeast Ddc2 and Rad9 but functions independently of Rad9 modification and Rad53 activation. Our results indicate that XATR is not functioning through the established mitotic checkpoint pathways. Instead, we find that the XATR suppression of the mec1 mutant checkpoint defect requires the spindle checkpoint factors Mad1 and Mad2, suggesting a role for XATR in the spindle assembly checkpoint. Finally, we show that a yeast strain expressing a truncated, kinase domain deleted form of mec1 from the endogenous locus is partially checkpoint proficient and induces a mitotic cell cycle arrest in a Mad2 dependent manner. Thus, the link between the non-catalytic region of the ATR kinase family and the spindle checkpoint pathway is conserved.

Authors

Troy D. McSherry

University of Chicago; Chicago, Illinois

Ana A. Kitazono

The University of Tennessee at Knoxville; Knoxville, Tennessee

Ali Javaheri

University of Chicago; Chicago, Illinois

Stephen J. Kron

University of Chicago; Chicago, Illinois

Paul Mueller

Prous Institute for Biomedical Research.com

Purchase article for $19

Subscribe to this journal for $129/year