Nucleotide sequence of the cytochrome oxidase subunit I gene from soybean mitochondria

Abstract

The cytochrome oxidase subunit I gene was isolated from a soybean mitochondrial library and subcloned into M13 for DNA sequencing. The sequences of the gene and flanking regions are presented and compared to the corresponding gene from maize. There is approximately 94% sequence homology between the soybean (dicot) and maize (monocot) coding sequences at the nucleotide level. The soybean sequence exists as a single copy in the mitochondrial genome and contains an open reading frame that could encode a polypeptide of 527 amino acids. There is very little sequence homology between the soybean and maize sequences upstream from the coding regions and none is detected downstream. Even the 3' ends of the COI coding regions differ considerably between soybean and maize. There are many amino acid differences at the carboxy terminus and the predicted polypeptide contains one less amino acid than the maize sequence. Northern analysis of the soybean mitochondrial RNA suggests that this region is actively transcribed and yields two major transcripts.