KA1-targeted regulatory domain mutations activate Chk1 in the absence of DNA damage

摘要: The Chk1 protein kinase is activated in response to DNA damage through ATR-mediated phosphorylation at multiple serine-glutamine (SQ) residues within the C-terminal regulatory domain, however molecular mechanism not understood. Modelling indicates a high probability that this region of contains kinase-associated 1 (KA1) small, compact fold found kinases including SOS2, AMPK and MARK3. We introduced mutations into designed disrupt specific structural elements predicted KA1 domain. Remarkably, six seven mutants exhibit constitutive biological activity (Chk1-CA) absence damage, profoundly arresting cells G2 phase cell cycle. Cell cycle arrest induced by selected Chk1-CA depends on catalytic activity, which increased several-fold compared wild-type, key ATR site serine 345 (S345) required. Thus, targeting putative domain confer circumventing need for positive phosphorylation.