Short-patch single-strand break repair in ataxia oculomotor apraxia-1

AOA1 (ataxia oculomotor apraxia-1) results from mutations in aprataxin, a component of DNA strand break repair that removes AMP from 5′-termini. In the present article, we provide an overview of this disease and review recent experiments demonstrating that short-patch repair of oxidative single-strand breaks in AOA1 cell extracts bypasses the point of aprataxin action and stalls at the final step of DNA ligation, resulting in accumulation of adenylated DNA nicks. Strikingly, this defect results from insufficient levels of non-adenylated DNA ligase and short-patch single-strand break repair can be restored in AOA1 extracts, independently of aprataxin, by addition of recombinant DNA ligase.