OsRPA2

Annotated Information

A homolog of replication protein A2 was isolated from rice that was termed OsRPA2. 

===Function

Replication protein A (RPA) is a heterotrimeric, singlestranded DNA-binding protein with several functions in DNA metabolism in humans and yeast and supposedly also in plants. OsRPA2, the 32-kDa subunit of RPA from rice (Oryza sativa L.).The plant-specific mechanisms of regulation have evolved for RPA2 within the generally well-conserved process of DNA replication, suggesting specific requirements for regulation of DNA metabolism in plants . Even though the precise function of RPA is still not clear, extensive, mostly biochemical analysis of RPA proteins in humans and yeast led to the conclusion that RPA plays essential roles in many aspects of nucleic acid metabolism, including DNA replication, but also DNA repair and DNA recombination .

Expression

Replication protein A (RPA) is a heterotrimeric protein complex, encoded by RPA1, RPA2 and RPA3.RPA binds single-stranded DNA during replication to stabilize DNA in the single-strand conformation. It stimulates DNA synthesisthrough interaction with DNA polymerase α. Mutations in RPA2 were found to be lethal in yeast(Philipova et al. 1996). Much less is known about RPA from plants. An RPA protein complex was isolated from tobacco by binding and elution from single-stranded DNA and was shown to induce DNA polymerase activity (Garcia-Maya and Buck 1997). From rice, cDNAs of the two subunits OsRPA1 (van der Knaap et al. 1997; Ishibashi et al.2001) and OsRPA2 (Ishibashi et al. 2001; this study) were isolated. The OsRPA1 gene was shown to be expressed mainly in proliferative tissues and was induced coordinately with cell cycle induction by gibberellic acid(van der Knaap 1997) and during re-growth after starvation of suspension cells (Ishibashi et al. 2001). The results of the gene and protein regulation of OsRPA2 from rice presented indicate that despite a high degree of conservation of RPA among eukaryotes, regulation of OsRPA2 displays features that appear to be specific to plants.In rice, OsRPA2 expression was regulated at the level of transcription as well as at the protein level. Regulation of OsRPA2 protein abundance appeared to occur at more than one level since induction of gene expression during S phase lagged behind elevated protein levels.

Evolution

Through PCR from a rice cDNA library (Sauter et al. 1995) using a gene-specific primer (bp 896–915) and a plasmid-derived primer (bp 798–817 of pBluescript II SK) ,a longer clone was obtained that included the coding region up to the start codon. To obtain the 5'-UTR of the cDNA, a 5'-rapid amplification of cDNA ends(5'-RACE; Gibco, Karlsruhe,Germany) was performed  using cDNA as template that was reverse-transcribed from total RNA isolated from the intercalary meristem of plants that were submerged for 6 h. The complete sequence with the encoded open reading frame was termed OsRPA2and was submitted to the nucleotide sequence database at EMBL (accession number AJ278822).

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Labs working on this gene

Department of Applied Biological Science,Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki,278-8510 Noda-shi, Chiba-ken, Tokyo, Japan

References

[1] Plant-specific regulation of replication protein A2 (OsRPA2) from rice during the cell cycle and in response to ultraviolet light exposure

 Planta, 2003, 217(3): 457-465.

[2]Wold MS (1997) Replication protein A: a heterotrimeric, singlestranded DNA-binding protein required for eukaryotic DNA metabolism. Annu Rev Biochem 66:61–92.

[3]Treuner K, Ramsperger U, Knippers R (1996) Replication protein A induces the unwinding of long double-stranded DNA regions. J Mol Biol 259:104–112.