Thompson R J, Mosig G
Department of Molecular Biology, Vanderbilt University, Nashville, TN 37235.
Nucleic Acids Res. 1988 Apr 25;16(8):3313-26. doi: 10.1093/nar/16.8.3313.
We show that in E. coli, a Chlamydomonas chloroplast promoter, PA, is repressed by Integration Host Factor (IHF). The himA 42 mutation, altering the alpha-subunit of E. coli IHF, leads to over-accumulation of PA transcripts in vivo. This effect requires upstream chloroplast DNA sequences. DNAase I and methylation protection experiments show that IHF binds in vitro to a site within PA and band-retardation shows that IHF inhibits formation of PA-E. coli RNA polymerase open complexes. We interpret these results, together with our previous deletion analyses, to mean that in E. coli, repression of PA by IHF minimally requires both binding of IHF to a site overlapping PA and binding of one or more additional proteins, perhaps including IHF itself, to sequences upstream of PA.
我们发现，在大肠杆菌中，衣藻叶绿体启动子PA受到整合宿主因子（IHF）的抑制。himA 42突变改变了大肠杆菌IHF的α亚基，导致体内PA转录本过度积累。这种效应需要叶绿体上游DNA序列。DNA酶I和甲基化保护实验表明，IHF在体外与PA内的一个位点结合，凝胶阻滞实验表明，IHF抑制PA-大肠杆菌RNA聚合酶开放复合物的形成。我们将这些结果与之前的缺失分析结合起来解释，意味着在大肠杆菌中，IHF对PA的抑制至少需要IHF与重叠PA的位点结合，以及一种或多种其他蛋白质（可能包括IHF本身）与PA上游序列结合。
