Chang Tianjun, Li Guangping, Ding Zhan, Li Weiguo, Zhu Panpan, Lei Wei, Shangguan Dihua
Henan Polytechnic University, Jiaozuo, 454000, P. R. China.
Institute of Resources and Environment, Henan Polytechnic University, Jiaozuo, 454003, P. R. China.
Chembiochem. 2022 Oct 19;23(20):e202200405. doi: 10.1002/cbic.202200405. Epub 2022 Sep 20.
G-quadruplexes (G4s) have been shown to be involved in the regulation of multiple cellular processes. Exploring putative G4-forming sequences (PQSs) in heat-responsive genes of rice and their folding structures under different conditions will help to understand the mechanism in response to heat stress. In this work, we discovered a prevalence of PQSs in nuclease hypersensitive sites within the promoters of heat-responsive genes. Moreover, 50 % of the searched G PQSs ((G L ) G ) locate in heat shock transcription factors. Circular dichroism spectroscopy, thermal difference spectroscopy, and UV melting analysis demonstrated the representative PQSs could adopt stable G4s at physiological temperature and potassium concentration. These PQSs were able to stall Klenow fragment (KF) DNA polymerase by the formation of G4s. However, the G4s with T values around 50-60 °C could be increasingly unwound by KF with the increase of temperatures from 25 to 50 °C, implying that these G4s could sense the changes in temperature by structural switch. This work offers fresh clues to understanding the potential of G4-involved functions of PQSs and the molecular events in plants in response to heat stress.
G-四链体（G4s）已被证明参与多种细胞过程的调控。探索水稻热响应基因中假定的G4形成序列（PQSs）及其在不同条件下的折叠结构，将有助于理解植物对热胁迫的响应机制。在这项研究中，我们发现热响应基因启动子内的核酸酶超敏位点普遍存在PQSs。此外，所搜索到的G PQSs（(G L ) G ）中有50%位于热休克转录因子中。圆二色光谱、热差光谱和紫外熔解分析表明，代表性的PQSs在生理温度和钾离子浓度下能够形成稳定的G4s。这些PQSs能够通过形成G4s来阻止Klenow片段（KF）DNA聚合酶的作用。然而，随着温度从25℃升高到50℃，熔解温度（Tm）约为50 - 60℃的G4s会被KF逐渐解开，这意味着这些G4s能够通过结构转换感知温度变化。这项工作为理解PQSs中G4相关功能的潜力以及植物响应热胁迫的分子事件提供了新线索。
