Activation of protein kinase Tel1 through recognition of protein-bound DNA ends.

Double-strand breaks (DSBs) in chromosomal DNA elicit a rapid signaling response through the ATM protein kinase. ATM corresponds to Tel1 in budding yeast. Here we show that Tel1 kinase activity is altered by protein binding at DNA ends via the Mre11-Rad50-Xrs2 (MRX) complex. Similar to ATM, Tel1 is activated through ...
interaction with the MRX complex and DNA ends. In vivo, Tel1 activation is enhanced in sae2Δ or mre11-3 mutants after camptothecin treatment, both of which are defective in the removal of topoisomerase I from DNA. In contrast, the sae2Δ mutation does not stimulate Tel1 activation after expression of EcoRI endonuclease that generates "clean" DNA ends. In an in vitro system, tethering Fab fragments to DNA ends inhibits MRX-mediated DNA end processing but enhances Tel1 kinase activation. The mre11-3 mutation abolishes DNA end-processing activity but does not affect the ability to enhance Tel1 activation. These results support the model in which MRX controls Tel1 activation by recognizing protein-bound DNA ends.
Date: Mar. 14, 2011
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