EXPRESSION OF THE PSBDII GENE IN SYNECHOCOCCUS SP STRAIN-PCC-7942 REQUIRES SEQUENCES DOWNSTREAM OF THE TRANSCRIPTION START SITE
EXPRESSION OF THE PSBDII GENE IN SYNECHOCOCCUS SP STRAIN-PCC-7942 REQUIRES SEQUENCES DOWNSTREAM OF THE TRANSCRIPTION START SITE
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DOI：
10.1128/jb.173.23.7525-7533.1991
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发表时间：
1991-12-01
影响因子：
3.2
通讯作者：
GOLDEN, SS
中科院分区：
文献类型：
--
作者：
BUSTOS, SA;GOLDEN, SS
聚球藻属菌株PCC 7942中的psbDI和psbDII基因编码D2多肽，D2多肽是光系统II反应中心的必需组分。 以前的研究表明，转录从psbDII，但不是psbDI，增加响应于高的光强度。 从聚球藻细胞转移到高光的可溶性蛋白质被发现具有从psbDII编码区上游的DNA序列的亲和力。 DNA迁移率变化和铜-菲咯啉足迹分析的一个258 bp的片段揭示了三个不同的DNA-蛋白质复合物，映射到+11和+84之间的非翻译前导区。 缺失上游侧翼区至-42对psbDII-lacZ报告基因的表达或其光诱导没有影响，而无启动子的构建体仅支持最低背景水平的β-半乳糖苷酶。 在第一个保护区的足迹内的4-bp的缺失，β-半乳糖苷酶活性降低到约2%的未删除的控制，但基因表达仍然响应于光。 删除这三个保护区完全取消基因表达和光诱导。 这些结果表明，psbDII基因需要有效的基因表达，其中之一可能参与调控光的非翻译前导区内的元素。
The psbDI and psbDII genes in Synechococcus sp. strain PCC 7942 encode the D2 polypeptide, an essential component of the photosystem II reaction center. Previous studies have demonstrated that transcripts from psbDII, but not psbDI, increase in response to high light intensity. Soluble proteins from Synechococcus cells shifted to high light were found to have affinity for DNA sequences upstream from the psbDII coding region. DNA mobility-shift and copper-phenanthroline footprinting assays of a 258-bp fragment revealed three distinct DNA-protein complexes that mapped to the untranslated leader region between +11 and +84. Deletion of the upstream flanking region to -42 had no effect on the expression of a psbDII-lacZ reporter gene or its induction by light, whereas a promoterless construct supported only minimal background levels of beta-galactosidase. A 4-bp deletion within the first protected region of the footprint decreased the beta-galactosidase activity to approximately 2% of that of the undeleted control, but gene expression remained responsive to light. Deletion of the three protected regions completely abolished both gene expression and light induction. These results suggest that the psbDII gene requires elements within the untranslated leader region for efficient gene expression, one of which may be involved in regulation by light.