Graduate School of Information Science, Nara Institute of Science and Technology, Takayama, Ikoma, Nara, Japan.
Nucleic Acids Res. 2011 Jan;39(2):414-28. doi: 10.1093/nar/gkq780. Epub 2010 Sep 3.
AbrB is a global transcriptional regulator of Bacillus subtilis that represses the expression of many genes during exponential growth. Here, we demonstrate that AbrB and its homolog Abh bind to hundreds of sites throughout the entire B. subtilis genome during exponential growth. Comparison of regional binding of AbrB and Abh in wild-type, ΔabrB and Δabh backgrounds revealed that they bind as homomer and/or heteromer forms with different specificities and affinities. We found four AbrB and Abh binding patterns were major. Three of these contain pairs of TGGNA motifs connected by A/T-rich sequences, differing in arrangement and spacing. We also assessed the direct involvement of these complexes in the control of gene expression. Our data indicate that AbrB usually acts as a repressor, and that the ability of Abh to act as a transcriptional regulator was limited. We found that changes to AbrB/Abh levels affect their binding at several promoters and consequently transcriptional regulation. Surprisingly, most AbrB/Abh binding events had no impact on transcription, suggesting an interesting possibility that AbrB/Abh binding is analogous to nucleoid-associated protein binding in Escherichia coli.
AbrB 是枯草芽孢杆菌的一种全局转录调控因子，在指数生长期抑制许多基因的表达。在这里，我们证明 AbrB 和它的同源物 Abh 在指数生长期在整个枯草芽孢杆菌基因组中结合到数百个位点。在野生型、ΔabrB 和 Δabh 背景下比较 AbrB 和 Abh 的区域结合，发现它们以同型或异型二聚体的形式结合，具有不同的特异性和亲和力。我们发现有四种 AbrB 和 Abh 结合模式是主要的。其中三种包含通过 A/T 丰富序列连接的 TGGNA 基序对，排列和间距不同。我们还评估了这些复合物在基因表达控制中的直接参与。我们的数据表明 AbrB 通常作为一个抑制剂，而 Abh 作为转录调节因子的能力是有限的。我们发现 AbrB/Abh 水平的变化会影响它们在几个启动子上的结合，从而影响转录调控。令人惊讶的是，大多数 AbrB/Abh 结合事件对转录没有影响，这表明一个有趣的可能性，即 AbrB/Abh 结合类似于大肠杆菌中的核小体相关蛋白结合。
