Characterization of the S7 ribosomal protein gene in wheat mitochondria

By screening a wheat mitoplast cDNA bank, we have identified an open reading frame of 444 bp that has a derived amino acid sequence homologous to bacterial-type S7 ribosomal proteins. This gene, designated rps7, is located upstream of one of two 26S rRNA gene copies in the wheat mitochondrial genome and is expressed as an abundant mRNA of approximately 0.7 kb. Its 5' terminus maps to the end of an 80 bp element that is closely related to sequences preceding the wheat coxII, orf25 and atp6 genes. Southern hybridization analysis indicates that rps7-homologous sequences are present in the mitochondria of rice and pea, but not soybean.