Nucleotide sequence of the frxB gene in wheat chloroplast DNA

DNA sequence analysis of part of the small single copy region of wheat (Triticum aestfvum cv. Mardler) chloroplast DNA has revealed an open reading frame of 528 bp. This open reading frame is located in the 11.0 kbp PstI fragment (P5), approximately 6.5 kbp from the 3' end of the nearer copy of the gene for the 23S rRNA (1). The gene is transcribed in the same direction as the nearer rRNA operon. The deduced amino acid sequence indicates a polypeptide of 176 amino acid residues which contains 70% residues identical to the product of a gene termed frxB in liverwort chloroplast DNA (2) and 78% residues identical to the product of 0RF167 in the tobacco chloroplast genome (3). Wheat frxB encodes a polypeptide of molecular weight 20393 which is predicted to carry two 4Fe-4S centres (4).