Abstract
Sulfite reductase (SiR) is localized in plastids, and catalyzes reduction of sulfite to sulfide, using electrons from ferredoxin. SiR is also a major component of plastid nucleoids. Degenerate primers were preparated from a sequence alignment of Arabidopsis, maize and tobacco to amplify DNA fragments by PCR from pea genome. Pea cDNA library was screened using these fragments as the probe. A cDNA coding an amino acid sequence started from midstream of the transit peptide and an overlapping one from another library were isolated. Since Southern analysis suggested a single PsSiR gene, a sequence of PsSiR cDNA was determined by joining the two partial sequences. In Northern analysis, the levels of transcript of PsSiR were similar in both light- and dark-grown 7-day old seedlings. Despite absence of obvious DNA-binding motif, gel mobility assay showed that SiR bound to plasmid vectors and E. coli chromosomal DNA fragments.
