Replication Protein A (RPA1a) Is Required for Meiotic and Somatic DNA Repair But Is Dispensable for DNA Replication and Homologous Recombination in Rice    

Abstract

Replication protein A (RPA), a highly conserved single-stranded DNA-binding protein in eukaryotes, is a stable complex comprising three subunits termed RPA1, RPA2, and RPA3. RPA is required for multiple processes in DNA metabolism such as replication, repair, and homologous recombination in yeast (Saccharomyces cerevisiae) and human. Most eukaryotic organisms, including fungi, insects, and vertebrates, have only a single RPA gene that encodes each RPA subunit. Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), however, possess multiple copies of an RPA gene. Rice has three paralogs each of RPA1 and RPA2, and one for RPA3. Previous studies have established their biochemical interactions in vitro and in vivo, but little is known about their exact function in rice. We examined the function of OsRPA1a in rice using a T-DNA insertional mutant. The osrpa1a mutants had a normal phenotype during vegetative growth but were sterile at the reproductive stage. Cytological examination confirmed that no embryo sac formed in female meiocytes and that abnormal chromosomal fragmentation occurred in male meiocytes after anaphase I. Compared with wild type, the osrpa1a mutant showed no visible defects in mitosis and chromosome pairing and synapsis during meiosis. In addition, the osrpa1a mutant was hypersensitive to ultraviolet-C irradiation and the DNA-damaging agents mitomycin C and methyl methanesulfonate. Thus, our data suggest that OsRPA1a plays an essential role in DNA repair but may not participate in, or at least is dispensable for, DNA replication and homologous recombination in rice.

MEIOTIC F-BOX Is Essential for Male Meiotic DNA Double-Strand Break Repair in Rice

“…In higher plants, DSB formation and repair is a prerequisite for homologous chromosome pairing, SC formation, and recombination during meiosis (Borde and de Massy, 2013). Many aspects of the mof mutant phenotype resemble those described for the mutants of genes involved in DSB processing and repair, such as osmre11, oscom1, osrad51c, rpa1a, and xrcc3 in rice (Chang et al, 2009;Ji et al, 2012Ji et al, , 2013Tang et al, 2014;Zhang et al, 2015). OsCOM1 is the homolog of COM1/SAE2 in S. cerevisiae, Ctp1 in fission yeast, and CtBP-interacting protein in mammals (McKee and Kleckner, 1997a;Prinz et al, 1997;Schaeper et al, 1998;Limbo et al, 2007).…”

DNA Damage Repair in the Context of Plant Chromatin

“…Arabidopsis and rice have multiple genes for the three subunit types, and mutants of the RPA1 types show different DNA sensitivity phenotypes, indicating specialization and redundancy at the same time (Chang et al, 2009;Aklilu et al, 2014). RPA2 mutants are affected in crossover formation in rice .…”

Role of RPA Proteins in Radiation Repair and Recovery

“…Higher plants contain multiple homologs of at least the large and medium subunits. In rice, one homolog of RPA1 is not essential during vegetative growth, but mutants are sterile, indicating a meiotic defect (Chang, et al, 2009). Also, mutants are sensitive to DNA-damaging agents, indicating a role in repair but not replication.…”

“…Like rice, Arabidopsis contains multiple homologs for the RPA1 and RPA2 subunits, but also has two RPA3 genes (Shultz, et al, 2007). In both plants, one of the large subunits has been shown to be non-essential for vegetative growth, but is required for meiosis, demonstrating specialization of function among the multiple species of protein (Chang, et al, 2009;Osman, et al, 2009). This homolog is involved in response to DNA damage as well as maintenance of telomeres (Takashi, et al, 2009).…”