DNA Damage Response and Checkpoint Adaptation in Saccharomyces cerevisiae: Distinct Roles for the Replication Protein A2 (Rfa2) N-Terminus

• NCJ Number: 249342
• Journal: Genetics Volume: 199 Issue: 3 Dated: March 2015
• Author(s): Padmaja L. Ghospurkar; Timothy M. Wilson; Amber L. Severson; Sarah J. Klein; Sakina K. Khaku; Andre P. Walther; Stuart J. Haring
• Date Published: March 2015
• Length: 0 pages
• Grant Number(s): 2004-RG-CX-K001
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored)

Annotation

This study used an aspartic acid/alanine-scanning and genetic interaction approach to delineate the importance of the phosphorylation domain in a DNA-damage response in budding yeast.

Abstract

In response to DNA damage, two general but fundamental processes occur in the cell: (1) a DNA lesion is recognized and repaired, and (2) concomitantly, the cell halts the cell cycle to provide a window of opportunity for repair to occur. An essential factor for a proper DNA-damage response is the heterotrimeric protein complex Replication Protein A (RPA). Of particular interest is hyperphosphorylation of the 32-kDa subunit, called RPA2, on its serine/threonine-rich amino (N) terminus following DNA damage in human cells. The unstructured N-terminus is often referred to as the phosphorylation domain and is conserved among eukaryotic RPA2 subunits, including Rfa2 in Saccharomyces cerevisiae. The current study determined that the Rfa2 N-terminus is important for a proper DNA-damage response in yeast, although its phosphorylation is not required. Subregions of the Rfa2 N-terminus important for the DNA-damage response were also identified. Finally, an Rfa2 N-terminal hyperphosphorylation-mimetic mutant behaves similarly to another Rfa1 mutant (rfa1-t11) with respect to genetic interactions, DNA-damage sensitivity, and checkpoint adaptation. Study data indicate that post-translational modification of the Rfa2 N-terminus is not required for cells to deal with "repairable" DNA damage; however, post-translational modification of this domain might influence whether cells proceed into M-phase in the continued presence of unrepaired DNA lesions as a "last-resort" mechanism for cell survival. (Publisher abstract modified)