Rapp W D, Lupold D S, Mack S, Stern D B
Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853.
Mol Cell Biol. 1993 Dec;13(12):7232-8. doi: 10.1128/mcb.13.12.7232-7238.1993.
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.
植物线粒体启动子的保守性较差，但通常共享一个跨度约为17个核苷酸的松散共有序列。我们之前利用同源体外转录系统表明，该区域内一个11个核苷酸的序列至少构成了玉米线粒体atp1启动子的一部分（W. Rapp和D. Stern，《欧洲分子生物学组织杂志》11:1065 - 1073，1992年）。我们通过使用一系列接头扫描和点突变来详细定义atp1启动子，扩展了这一发现。我们的结果表明，相对于主要转录起始位点，-12至 +5位的突变可将起始率降低至野生型水平的<10%至40%之间。分布在该区域的一些突变影响较小或无影响。综合来看，我们的数据表明了一个模型，其中atp1启动子由一个从 -7延伸至 +5的中央结构域和一个以 -11至 -12为中心的1至3个碱基对的上游结构域组成。由于该启动子区域内的许多突变在体外是可耐受的，玉米atp1启动子与高度保守的酵母线粒体启动子不同。
