Molecular characterisationof a bean chloroplastic 2-Cys peroxiredoxin

A 2-Cys peroxiredoxin (Prx) named Pvprx was purified from Phaseolus vulgaris leaves. Cloning and sequencing of the cDNA and of the gene were achieved using degenerated oligonucleotides designed from partial sequences of peptides and polymerase chain reaction (PCR) techniques. Comparison of the sequences of the cDNA and of the gene revealed the presence of six introns interrupting the coding region. Southern blot analysis suggested the existence of a small Pvprx multigene family in P. vulgaris comprising at least two members. All sequence features of animal and plant 2-Cys Prxs were conserved in Pvprx. The purified protein was shown to have a protective effect against plasmid DNA cleavage by reactive oxygen species. The targeting to chloroplasts was demonstrated by fusion of its putative transit peptide to the green fluorescent protein (GFP). Accumulation of 1.5 and 1.3 kb mRNAs homologous to two Pvprx specific probes was found in roots, stems and leaves, with a preferential accumulation of 1.5 kb mRNAs in roots and stems. No major changes in the level of accumulation of 1.5 and 1.3 kb mRNAs were found in leaves sprayed with mercuric chloride.