Sumoylation influences DNA break repair partly by increasing the solubility of a conserved end resection protein.

Prabha Sarangi,Veronika Altmannova,Matthew C Whitby,Xiaolan Zhao,Tanya T Paull,Roland Steinacher,Lumir Krejci,Qiong Fu,Sue Jinks-Robertson

doi:10.1371/journal.pgen.1004899

Abstract

Protein modifications regulate both DNA repair levels and pathway choice. How each modification achieves regulatory effects and how different modifications collaborate with each other are important questions to be answered. Here, we show that sumoylation regulates double-strand break repair partly by modifying the end resection factor Sae2. This modification is conserved from yeast to humans, and is induced by DNA damage. We mapped the sumoylation site of Sae2 to a single lysine in its self-association domain. Abolishing Sae2 sumoylation by mutating this lysine to arginine impaired Sae2 function in the processing and repair of multiple types of DNA breaks. We found that Sae2 sumoylation occurs independently of its phosphorylation, and the two modifications act in synergy to increase soluble forms of Sae2. We also provide evidence that sumoylation of the Sae2-binding nuclease, the Mre11-Rad50-Xrs2 complex, further increases end resection. These findings reveal a novel role for sumoylation in DNA repair by regulating the solubility of an end resection factor. They also show that collaboration between different modifications and among multiple substrates leads to a stronger biological effect.

Highlights

Efficient and accurate genome repair requires regulatory mechanisms that adjust DNA repair levels and pathway usage depending on the cellular context
We and others recently reported that five proteins involved in DNA end resection are sumoylated upon DNA damage in budding yeast [17,18]
We found that combining the K97R and 3A mutations, or the K97R and S267A mutations, resulted in greater sensitivity to methyl methanesulfonate (MMS) and CPT compared to mutants that were defective for only one modification (Fig. 3E–3F)

Summary

Introduction

Efficient and accurate genome repair requires regulatory mechanisms that adjust DNA repair levels and pathway usage depending on the cellular context. In response to increased lesion loads, DNA repair pathways are upregulated [1,2,3]. The regulatory changes in these situations occur rapidly, involve many targets, and are reversible [1,2,3]. They are often enabled by protein modifications that reversibly add modifier groups to multiple targets. The best-illustrated example of this is protein phosphorylation mediated by the DNA damage checkpoint and cyclin-dependent kinases, which occurs within minutes of changes in repair needs and affects hundreds of protein targets The best-illustrated example of this is protein phosphorylation mediated by the DNA damage checkpoint and cyclin-dependent kinases, which occurs within minutes of changes in repair needs and affects hundreds of protein targets (e.g. [6,7,8,9])

Methods

Results

Conclusion