Oliveira Paulo, Lindblad Peter
Department of Physiological Botany, EBC, Uppsala University, Villavägen 6, SE-752 36 Uppsala, Sweden.
FEMS Microbiol Lett. 2005 Oct 1;251(1):59-66. doi: 10.1016/j.femsle.2005.07.024.
The unicellular cyanobacterium Synechocystis PCC 6803 contains a single pentameric bidirectional hydrogenase encoded by hoxEFUYH. Transcriptional experiments demonstrated that the five hox genes are part of a single transcript together with three ORFs with unknown functions. The transcription start point was localized by 5' RACE to 168bp upstream the hoxE ATG start codon. DNA affinity assays demonstrated a specific interaction between the hox regulatory promoter region and a protein which, using mass spectrometry, was identified to be LexA. Overexpressed His-tagged Synechocystis LexA and EMSA showed a specific binding to the promoter region of the hox operon. Increasing concentrations of the purified LexA resulted in two retarded LexA-DNA complexes, in agreement with the presence of two putative LexA binding sites upstream the determined TSP.
单细胞蓝藻集胞藻PCC 6803含有一种由hoxEFUYH编码的单一五聚体双向氢化酶。转录实验表明，五个hox基因与三个功能未知的开放阅读框（ORF）共同构成了一个单一转录本的一部分。转录起始点通过5' RACE定位到hoxE起始密码子ATG上游168bp处。DNA亲和分析表明，hox调控启动子区域与一种蛋白质之间存在特异性相互作用，通过质谱鉴定该蛋白质为LexA。过表达的His标签集胞藻LexA和电泳迁移率变动分析（EMSA）表明，其与hox操纵子的启动子区域存在特异性结合。纯化的LexA浓度增加导致出现两种滞后的LexA-DNA复合物，这与在确定的转录起始点（TSP）上游存在两个假定的LexA结合位点一致。
