A novel type of DNA curvature present in a Clostridium perfringens ferredoxin gene:: characterization and role in gene expression
A novel type of DNA curvature present in a Clostridium perfringens ferredoxin gene:: characterization and role in gene expression
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DOI：
10.1099/mic.0.26503-0
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发表时间：
2003-11-01
期刊：
影响因子：
2.8
通讯作者：
Okabe, A
中科院分区：
文献类型：
--
作者：
Kaji, M;Matsushita, O;Okabe, A
这项研究表明，产气荚膜梭菌铁氧还蛋白基因（per-fdx）具有一种新型的DNA弯曲，它是由5个阶段的A-束从上游延伸到下游的-35区。启动子上游的三个A区和启动子内的两个A区位于对应于C.产气荚膜杆菌磷脂酶C基因（plc）和巴氏梭菌铁氧还蛋白基因（pas-fdx）。将per-fdx、pas-fdx和plc基因的DNA片段（相对于转录起始位点的核苷酸位置-69至+1）与质粒pPSV上的氯霉素乙酰转移酶报告基因融合，并通过测定每种C.产气荚膜杆菌属比较三个构建体的启动子活性，从高到低依次为per-fdx、pas-fdx和plc。缺失的三个上游A-tracts的per-fdx基因大大降低了启动子的活性，如前所述的PLC启动子。最下游A束的取代降低了per-fdx和pas-fdx基因的启动子活性。这些结果表明，不仅启动子上游的定相A-束，而且启动子内的那些也刺激启动子活性，并且表明per-fdx启动子的高活性是由于这两种类型的A-束的组合效应。
This study has revealed that a Clostridium perfringens ferredoxin gene (per-fdx) possesses a novel type of DNA curvature, which is formed by five phased A-tracts extending from upstream to downstream of the -35 region. The three A-tracts upstream of the promoter and the two within the promoter are located at the positions corresponding to A-tracts present in a C. perfringens phospholipase C gene (plc) and a Clostridium pasteurianum ferredoxin gene (pas-fdx), respectively. DNA fragments of the per-fdx, pas-fdx and plc genes (nucleotide positions -69 to +1 relative to the transcription initiation site) were fused to a chloramphenicol acetyltransferase reporter gene on a plasmid, pPSV, and their in vivo promoter activities were examined by assaying the chloramphenicol acetyltransferase activity of each C. perfringens transformant. Comparison of the three constructs showed that the order of promoter activity is, in descending order, per-fdx, pas-fdx and plc. Deletion of the three upstream A-tracts of the per-fdx gene drastically decreased the promoter activity, as demonstrated previously for the plc promoter. Substitution of the most downstream A-tract decreased the promoter activities of the per-fdx and pas-fdx genes. These results indicate that not only the phased A-tracts upstream of the promoter but also those within the promoter stimulate the promoter activity, and suggest that the high activity of the per-fdx promoter is due to the combined effects of these two types of A-tracts.