Reference "The rice mitochondrial nad3 gene has an extended reading frame at its 5' end: nucleotide sequence analysis of rice trnS, nad3, and rps12 genes"

Reference ID

4323

Title

The rice mitochondrial nad3 gene has an extended reading frame at its 5' end: nucleotide sequence analysis of rice trnS, nad3, and rps12 genes

Source

Current genetics, 1991, vol. 20, pp. 331-337

Authors (5)

Suzuki-T	Kazama-S
Hirai-A	Akihama-T
Kadowaki-K

Abstract

The nucleotide sequences of the tRNASer (trnS), pseudo-tRNA, NADH dehydrogenase
subunit 3 (nad3), and ribosomal protein S12 (rps12) genes from rice
mitochondrial DNA (mtDNA) were determined. Both trnS and nad3 were confirmed to
be single copy genes by Southern blot analysis. The nad3 and rps12 genes were
arranged in tandem, and the two were co-transcribed. The order of the above four
genes in rice mtDNA differed from the linear order observed for the wheat and
maize genes. In rice mitochondria, the trnS and pseudo-tRNA genes were found
upstream of the cytochrome c oxidase subunit I gene, instead of the nad3 and
rps12 genes as observed in maize and wheat. Additionally, while the rice nad3
and rps12 genes remain paired, they too are in a different sequence environment
from the wheat and maize genes. The apparent split of the two pairs of genes
indicates the occurrence of a mitochondrial intramolecular recombinational
event. Another peculiarity is that the sequence upstream of the translational
initiation codon of the rice nad3 gene is different from that of the wheat and
maize versions. The ATG initiation codon of wheat and maize nad3 is replaced by
TTG in the rice nad3. A subsequent deduction of the amino acid sequence,
accompanied by a primer extension analysis, indicates that the predicted rice
NAD3 protein has an additional 37 amino acid residues at its N-terminus compared
to the wheat and maize NAD3 proteins. cDNA sequence analysis showed no introns
or the occurrence of RNA editing at the newly replaced TTG codon.