A chloroplast-derived sequence is utilized as a source of promoter sequences for the gene for subunit 9 of NADH dehydrogenase (nad9) in rice mitochondria.
The chloroplast-derived sequence trnS-rps4/ 3'trnL-trnF-ndhJ-ndhK (4066 bases in length) is present in a region that starts 355 bases upstream of the gene for subunit 9 of NADH dehydrogenase (nad9) in the mitochondrial genome of rice. Northern blot hybridization revealed that three large transcripts of 3.05, 1.62 and 1.05 kb hybridized to strand-specific probes for both the nad9 gene and the chloroplast-derived sequence, indicating that the nad9 gene was transcribed together with the chloroplast-derived sequence. From the results of in vitro capping and ribonuclease protection experiments, as well as primer extension analysis, we identified at least seven sites for the initiation of transcription of nad9 in the chloroplast-derived sequence. All of the initiation sites for transcription of the nad9 gene were located in sequences homologous to chloroplast DNA. Two of seven initiation sites were flanked by a sequence homologous to the consensus promoter motif that includes the CRTA motif (where R is A or G) of the rice mitochondrion. However, the sequences surrounding the other five sites showed only limited similarity to the conserved sequence. It is suggested that all the promoters of the rice nad9 gene exist in a sequence that was transferred from the chloroplast during evolution. Thus, the chloroplast-derived sequence has a novel, significant function in the mitochondrial genome of this higher plant.
Nakazono
M
M
Laboratory of Radiation Genetics, Faculty of Agriculture, University of Tokyo, Japan.
Nishiwaki
S
S
Tsutsumi
N
N
Hirai
A
A
D001483:Base Sequence; D015152:Blotting, Northern; D002736:Chloroplasts / Q000235:genetics*; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017403:In Situ Hybridization; D024101:Mitochondrial Proteins; D009245:NADH Dehydrogenase / Q000235:genetics; D012275:Oryza / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012360:RNA, Transfer, Phe / Q000235:genetics; D012361:RNA, Transfer, Pro / Q000235:genetics; D012362:RNA, Transfer, Ser / Q000235:genetics; D014158:Transcription, Genetic
D017931:DNA Primers; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D024101:Mitochondrial Proteins; D010940:Plant Proteins; D012360:RNA, Transfer, Phe; D012361:RNA, Transfer, Pro; D012362:RNA, Transfer, Ser; C097421:rps4 protein, plant; D009245:NADH Dehydrogenase