DNA sequence-specific fluorescent dimeric bisbenzimidazoles DBP(n) and DBPA(n), noncovalently interacting with A-T pairs in the minor groove of double-stranded DNA were used for studying and monitoring the expression of histone-like H-NS-dependent promoters. Histone-like H-NS selectively binds to AT-rich segments of DNA and silences a large number of genes in bacterial chromosomes. The H-NS-dependent promoters of Quorum Sensing (QS)-regulated lux operons of the marine bacteria mesophilic Aliivibrio fischeri, psychrophilic Aliivibrio logei were used. Escherichia coli lux biosensors were constructed by cloning fragments bearing QS-regulated promoters into the vector, thereby placing each fragment upstream of the promoterless Photorhabdus luminescens luxCDABE genes. It was shown that the dimeric bisbenzimidazoles DBP(n) and DBPA(n) counteract the H-NS silencing activity. Thus, the presence of DBP(n) or DBPA(n) in the medium leads to an approximately 10–100-fold increase in the level of transcription of QS promoters in E. coli hns⁺. The largest decrease in the level of H-NS repression was observed using ligands containing a linker with a length of ca. 18 Å, such as DBP(2) and DBPA(2). Ligands containing linkers with n = 1 and 3 are an order of magnitude less active; ligands with n = 4 are inactive. DBPA(2) exhibits activity starting with a concentration of 0.5 μM; the minimum concentration of DBP(2) is 5–7 times higher. It is suggested that A-T pairs located at five nucleotide pair intervals, which correspond to the linker length in highly active ligands with n = 2, play a key role in the structure of H-NS-binding sites in QS-regulated promoters.

DNA序列特异性荧光二聚双苯并咪唑DBP（n）和DBPA（n）与双链DNA小沟中的AT对非共价相互作用，用于研究和监测组蛋白样H-NS依赖性启动子的表达。像组蛋白的H-NS选择性地结合到富含AT的DNA片段上，并使细菌染色体中的大量基因沉默。使用了Quorum Sensing（QS）调控的H-NS依赖性启动子，调节了海洋细菌中温嗜热Aliivibrio fischeri，嗜冷Aliivibrio logei的lux操纵子。通过将带有QS调控启动子的片段克隆到载体中来构建大肠杆菌lux生物传感器，从而将每个片段置于无启动子的上游发光光杆菌luxCDABE基因。结果表明，二聚双苯并咪唑DBP（n）和DBPA（n）抵消了H-NS沉默活性。因此，培养基中DBP（n）或DBPA（n）的存在会导致大肠杆菌hns ⁺中QS启动子的转录水平提高大约10-100倍。使用含有长度为ca的接头的配体观察到H-NS抑制水平的最大下降。18Å，例如DBP（2）和DBPA（2）。包含n = 1和3的连接基的配体的活性低一个数量级；n = 4的配体是无活性的。DBPA（2）的活性从0.5μM的浓度开始；DBP（2）的最低浓度高5至7倍。提示位于5个核苷酸对间隔的AT对在QS调控启动子的H-NS结合位点的结构中起着关键作用，该间隔对应于n = 2的高活性配体中的接头长度。