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Aqueous zinc‐ion batteries (AZIBs) have garnered significant research interest as promising next‐generation energy storage technologies owing to their affordability and high level of safety. However, their restricted ionic conductivity at subzero temperatures, along with dendrite formation and subsequent side reactions, unavoidably hinder the implementation of grid‐scale applications. In this study, a novel bimetallic cation‐enhanced gel polymer electrolyte (Ni/Zn‐GPE) was engineered to address these issues. The Ni/Zn‐GPE effectively disrupted the hydrogen‐bonding network of water, resulting in a significant reduction in the freezing point of the electrolyte. Consequently, the designed electrolyte demonstrates an impressive ionic conductivity of 28.70 mS cm−1 at −20°C. In addition, Ni2+ creates an electrostatic shielding interphase on the Zn surface, which confines the sequential Zn2+ nucleation and deposition to the Zn (002) crystal plane. Moreover, the intrinsically high activation energy of the Zn (002) crystal plane generated a dense and dendrite‐free plating/stripping morphology and resisted side reactions. Consequently, symmetrical batteries can achieve over 2700 hours of reversible cycling at 5 mA cm−2, while the Zn || V2O5 battery retains 85.3% capacity after 1000 cycles at −20°C. This study provides novel insights for the development and design of reversible low‐temperature zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

A working model for histone H3-induced dynamic regulation of the de novo DNA methyltransferase. DNA methyltransferase autoinhibition and activation DNA methylation is established during embryogenesis by the de novo DNA methyltransferases DNMT3A and DNMT3B. Here, Yanhui Xu and colleagues determine crystal structures of DNMT3L (a catalytically inactive DNMT3 paralogue that stimulates the enzymatic activity of Dnmt3a) bound to DNMT3A and histone H3. The structure reveals an unexpected autoinhibitory conformation in the absence of histone H3, and a mechanism of H3-induced activation. DNA methylation is an important epigenetic modification that is essential for various developmental processes through regulating gene expression, genomic imprinting, and epigenetic inheritance.sup.1,2,3,4,5. Mammalian genomic DNA methylation is established during embryogenesis by de novo DNA methyltransferases, DNMT3A and DNMT3B.sup.6,7,8, and the methylation patterns vary with developmental stages and cell types.sup.9,10,11,12. DNA methyltransferase 3-like protein (DNMT3L) is a catalytically inactive paralogue of DNMT3 enzymes, which stimulates the enzymatic activity of Dnmt3a.sup.13. Recent studies have established a connection between DNA methylation and histone modifications, and revealed a histone-guided mechanism for the establishment of DNA methylation.sup.14. The ATRX-DNMT3-DNMT3L (ADD) domain of Dnmt3a recognizes unmethylated histone H3 (H3K4me0).sup.15,16,17. The histone H3 tail stimulates the enzymatic activity of Dnmt3a in vitro.sup.17,18, whereas the molecular mechanism remains elusive. Here we show that DNMT3A exists in an autoinhibitory form and that the histone H3 tail stimulates its activity in a DNMT3L-independent manner. We determine the crystal structures of DNMT3A-DNMT3L (autoinhibitory form) and DNMT3A-DNMT3L-H3 (active form) complexes at 3.82 and 2.90 Å resolution, respectively. Structural and biochemical analyses indicate that the ADD domain of DNMT3A interacts with and inhibits enzymatic activity of the catalytic domain (CD) through blocking its DNA-binding affinity. Histone H3 (but not H3K4me3) disrupts ADD-CD interaction, induces a large movement of the ADD domain, and thus releases the autoinhibition of DNMT3A. The finding adds another layer of regulation of DNA methylation to ensure that the enzyme is mainly activated at proper targeting loci when unmethylated H3K4 is present, and strongly supports a negative correlation between H3K4me3 and DNA methylation across the mammalian genome.sup.9,10,19,20. Our study provides a new insight into an unexpected autoinhibition and histone H3-induced activation of the de novo DNA methyltransferase after its initial genomic positioning., Author(s): Xue Guo [sup.1] [sup.2] , Ling Wang [sup.1] [sup.2] , Jie Li [sup.1] , Zhanyu Ding [sup.3] , Jianxiong Xiao [sup.1] , Xiaotong Yin [sup.1] , Shuang He [sup.1] [...]