Architecture of the maize mitochondrial atp1 promoter as determined by linker-scanning and point mutagenesis.
Plant mitochondrial promoters are poorly conserved but generally share a loose consensus sequence spanning approximately 17 nucleotides. Using a homologous in vitro transcription system, we have previously shown that an 11-nucleotide sequence within this region comprises at least part of the maize mitochondrial atp1 promoter (W. Rapp and D. Stern, EMBO J. 11:1065-1073, 1992). We have extended this finding by using a series of linker-scanning and point mutations to define the atp1 promoter in detail. Our results show that mutations at positions -12 to +5, relative to the major transcription start site, can decrease initiation rates to between < 10 and 40% of wild-type levels. Some mutations, scattered throughout this region, have lesser effects or no effect. Taken together, our data suggest a model in which the atp1 promoter consists of a central domain extending from -7 to +5 and an upstream domain of 1 to 3 bp that is centered around -11 to -12. Because many mutations within this promoter region are tolerated in vitro, the maize atp1 promoter is distinct from the highly conserved yeast mitochondrial promoters.
Rapp
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WD
Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853.
Lupold
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DS
Mack
S
S
Stern
D B
DB
D001483:Base Sequence; D016384:Consensus Sequence; D004272:DNA, Mitochondrial / Q000235:genetics; D017343:Genes, Plant; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D006180:Proton-Translocating ATPases / Q000235:genetics; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
D004272:DNA, Mitochondrial; D006180:Proton-Translocating ATPases