Phosphorylation and Cellular Function of the Human Rpa2 N-terminus in the Budding Yeast Saccharomyces Cerevisiae

• NCJ Number: 249316
• Journal: Experimental Cell Research Volume: 331 Issue: 1 Dated: February 2015 Pages: 183-199
• Author(s): Padmaja L. Ghospurkar; Timothy M. Wilson; Shengqin Liu; Anna Heraut; Jenna Steffes; Erica N. Mueller; Gregory G. Oakley; Stuart J. Haring
• Date Published: February 2015
• Length: 17 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 examined the sequence of differences and the functional interchangeability of orthologous Replication Protein A (RPA) subunits or regions, so as to provide insight into important regions and their functions and also might allow for study in simpler systems.

Abstract

Maintenance of genome integrity is critical for proper cell growth. This occurs through accurate DNA replication and repair of DNA lesions. A key factor involved in both DNA replication and the DNA damage response is the heterotrimeric single-stranded DNA (ssDNA) binding complex Replication Protein A (RPA). Although the RPA complex appears to be structurally conserved throughout eukaryotes, the primary amino acid sequence of each subunit can vary considerably. The current study determined that substitution of yeast Replication Factor A (RFA) with human RPA does not support yeast cell viability. Exchange of a single yeast RFA subunit with the corresponding human RPA subunit does not function due to lack of inter-species subunit interactions. Substitution of yeast Rfa2 with domains/regions of human Rpa2 important for Rpa2 function (i.e., the N-terminus and the loop 3-4 region) supports viability in yeast cells, and hybrid proteins containing human Rpa2 N-terminal phospho-mutations result in similar DNA damage phenotypes to analogous yeast Rfa2 N-terminal phospho-mutants. Finally, the human Rpa2 N-terminus (NT) fused to yeast Rfa2 is phosphorylated in a manner similar to human Rpa2 in human cells, indicating that conserved kinases recognize the human domain in yeast. The implication is that budding yeast represents a potential model system for studying not only human Rpa2 N-terminal phosphorylation, but also phosphorylation of Rpa2 N-termini from other eukaryotic organisms. (Publisher abstract modified)