Wadsworth Center, New York State Department of Health, Albany, New York, USA.
Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, New York, USA.
Microbiology (Reading). 2024 Jul;170(7). doi: 10.1099/mic.0.001474.
DnaA is a widely conserved DNA-binding protein that is essential for the initiation of DNA replication in many bacterial species, including . Cooperative binding of ATP-bound DnaA to multiple 9mer sites ('DnaA boxes') at the origin of replication results in local unwinding of the DNA and recruitment of the replication machinery. DnaA also functions as a transcription regulator by binding to DNA sites upstream of target genes. Previous studies have identified many sites of direct positive and negative regulation by DnaA. Here, we use a ChIP-seq to map the DnaA-binding landscape. Our data reveal a compact regulon for DnaA that coordinates the initiation of DNA replication with expression of genes associated with nucleotide synthesis, replication, DNA repair and RNA metabolism. We also show that DnaA binds preferentially to pairs of DnaA boxes spaced 2 or 3 bp apart. Mutation of either the upstream or downstream site in a pair disrupts DnaA binding, as does altering the spacing between sites. We conclude that binding of DnaA at almost all target sites requires a dimer of DnaA, with each subunit making critical contacts with a DnaA box.
DnaA 是一种广泛保守的 DNA 结合蛋白,对于许多细菌物种的 DNA 复制起始至关重要,包括 。ATP 结合的 DnaA 与复制起点处的多个 9mer 位点(“DnaA 盒”)的协同结合导致 DNA 的局部解旋,并募集复制机制。DnaA 还通过结合靶基因上游的 DNA 位点作为转录调节剂发挥作用。先前的研究已经确定了 DnaA 的许多直接正调控和负调控位点。在这里,我们使用 ChIP-seq 来绘制 DnaA 结合图谱。我们的数据揭示了 DnaA 的一个紧凑调控基因,它协调 DNA 复制的起始与与核苷酸合成、复制、DNA 修复和 RNA 代谢相关的基因的表达。我们还表明,DnaA 优先结合间隔 2 或 3bp 的 DnaA 盒对。在一对中的上游或下游位点的突变会破坏 DnaA 结合,改变位点之间的间隔也是如此。我们得出结论,DnaA 在几乎所有靶位点的结合都需要 DnaA 二聚体,每个亚基与 DnaA 盒形成关键接触。