Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX 77030, USA.
Nucleic Acids Res. 2023 Oct 13;51(18):9643-9657. doi: 10.1093/nar/gkad684.
Sequences capable of forming quadruplex or G4 DNA are prevalent in the promoter regions. The transformation from canonical to non-canonical secondary structure apparently regulates transcription of a number of human genes. In the budding yeast Saccharomyces cerevisiae, we identified 37 genes with a G4 motif in the promoters including 20 genes that contain stress response element (STRE) overlapping a G4 motif. STRE is the binding site of stress response regulators Msn2 and Msn4, transcription factors belonging to the C2H2 zinc-finger protein family. We show here that Msn2 binds directly to the G4 DNA structure through its zinc-finger domain with a dissociation constant similar to that of STRE-binding and that, in a stress condition, Msn2 is enriched at G4 DNA-forming loci in the yeast genome. For a large fraction of genes with G4/STRE-containing promoters, treating with G4-ligands led to significant elevations in transcription levels. Such transcriptional elevation was greatly diminished in a msn2Δ msn4Δ background and was partly muted when the G4 motif was disrupted. Taken together, our data suggest that G4 DNA could be an alternative binding site of Msn2 in addition to STRE, and that G4 DNA formation could be an important element of transcriptional regulation in yeast.
在启动子区域中，能够形成四链体或 G4 DNA 的序列很常见。从规范的二级结构到非规范的二级结构的转变显然调节了许多人类基因的转录。在 budding 酵母 Saccharomyces cerevisiae 中，我们在启动子中鉴定出 37 个具有 G4 基序的基因，其中 20 个基因包含重叠 G4 基序的应激反应元件 (STRE)。STRE 是应激反应调节剂 Msn2 和 Msn4 的结合位点，转录因子属于 C2H2 锌指蛋白家族。我们在这里表明，Msn2 通过其锌指结构域直接与 G4 DNA 结构结合，解离常数与 STRE 结合相似，并且在应激条件下，Msn2 在酵母基因组中形成 G4 DNA 的基因座处富集。对于具有 G4/STRE 包含启动子的大多数基因，用 G4 配体处理会导致转录水平显著升高。在 msn2Δ msn4Δ 背景下，这种转录升高大大降低，并且当 G4 基序被破坏时，部分减弱。总之，我们的数据表明，G4 DNA 除了 STRE 之外，可能是 Msn2 的另一个结合位点，并且 G4 DNA 的形成可能是酵母转录调控的一个重要因素。
