Reversible DNA Compaction by Sulfite Reductase Regulates Transcriptional Activity of Chloroplast Nucleoids*
Reversible DNA Compaction by Sulfite Reductase Regulates Transcriptional Activity of Chloroplast Nucleoids*
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亚硫酸还原酶可逆 DNA 压缩调节叶绿体核苷的转录活性*
DOI：
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发表时间：
2002
影响因子：
4.8
通讯作者：
N. Sato
中科院分区：
文献类型：
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作者：
Kohsuke Sekine;T. Hase;N. Sato
类核的转录活性在质体发育过程中发生变化，推测是由于类核的形态和分子差异所致。豌豆叶绿体类核中含有丰富的70 kDa亚硫酸还原酶（SiR）蛋白，该蛋白能使DNA紧密结合。使用体外转录测定，我们在这里表明，肝素增加了叶绿体类核的转录活性，伴随着SiR的释放。用荧光法分析叶绿体DNA的致密化，发现加入SiR后，叶绿体DNA的荧光强度降低，加入肝素后，荧光强度增加。外源SiR的加入使类核蛋白的致密化增强，肝素的加入使类核蛋白的致密化减弱，SiR有效地抑制了类核蛋白的体外转录活性，并抵消了肝素对类核蛋白的激活。这些结果表明，SiR通过改变DNA压缩来调节叶绿体类核的转录活性。
The transcriptional activity of nucleoids changes during plastid development, presumably due to the morphological and molecular differences of the nucleoids. Pea chloroplast nucleoids have an abundant 70-kDa protein identified as sulfite reductase (SiR) that can compact DNA. Using an in vitro transcription assay, we show here that heparin increased the transcriptional activity of chloroplast nucleoids with concomitant release of SiR. Using a fluorometric method we developed for analyzing DNA compaction, we found that the fluorescence intensity of chloroplast DNA stained with 4′,6-diamidino-2-phenylindole was decreased by the addition of SiR and increased by the subsequent addition of heparin. Addition of exogenous SiR increased the compaction of isolated nucleoids, and the addition of heparin relaxed it. SiR effectively repressed the in vitro transcription activity of nucleoids and counteracted the activation by heparin. These results suggest that SiR regulates the transcriptional activity of chloroplast nucleoids through changes in DNA compaction.