Error-free replication of DNA is essential for life. Despite the proofreading capability of several polymerases, intrinsic polymerase fidelity is in general much higher than what base-pairing energies can provide. Although researchers have investigated this long-standing question with kinetics, structural determination, and computational simulations, the structural factors that dictate polymerase fidelity are not fully resolved. Time-resolved crystallography has elucidated correct nucleotide incorporation and established a three-metal-ion-dependent catalytic mechanism for polymerases. Using X-ray time-resolved crystallography, we visualize the complete DNA misincorporation process catalyzed by DNA polymerase η. The resulting molecular snapshots suggest primer 3´-OH alignment mediated by A-site metal ion binding is the key step in substrate discrimination. Moreover, we observe that C-site metal ion binding preceded the nucleotidyl transfer reaction and demonstrate that the C-site metal ion is strictly required for misincorporation. Our results highlight the essential but separate roles of the three metal ions in DNA synthesis.
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http://dx.doi.org/10.1038/s41467-022-30005-3 | DOI Listing |
Chem Asian J
January 2025
East China University of Science and Technology, Institute of Fine Chemicals, Meilong Road, 200237, Shanghai, CHINA.
Oxidation of thia-pentapyrrane S-P4 with terminal β-linked pyrrole and thiophene units in the presence of various metal ions has been found to afford distinct porphyrinoids. Specifically, N-confused thiasapphyrin (1), Cu(III) norrole (2), neo-confused phlorin (3), and p-benzinorrole (4) were obtained, when S-P4 was oxidized with p-chloranil in acetonitrile in the presence of Ni2+, Cu2+, Cd2+, and Co2+, respectively. The structures of 1-4 have been clearly elucidated by NMR spectroscopy, HRMS, and X-ray crystal diffraction (for 2-4).
View Article and Find Full Text PDFProtein Sci
February 2025
Department of Physics, University of Washington, Seattle, Washington, USA.
Proteins' flexibility is a feature in communicating changes in cell signaling instigated by binding with secondary messengers, such as calcium ions, associated with the coordination of muscle contraction, neurotransmitter release, and gene expression. When binding with the disordered parts of a protein, calcium ions must balance their charge states with the shape of calcium-binding proteins and their versatile pool of partners depending on the circumstances they transmit. Accurately determining the ionic charges of those ions is essential for understanding their role in such processes.
View Article and Find Full Text PDFSci Rep
January 2025
School of Agriculture and Food Systems, Davis College of Agriculture and Natural Resources, West Virginia University, Morgantown, WV, USA.
The management of micronutrients, such as boron (B) and zinc (Zn), is critical for plant growth and crop yields. One method of rapid intervention crop management to mitigate nutritional deficiency is the foliar supply of B and Zn. Our study investigates the effect of foliar-supplied B and Zn availability on the global transcriptional modulation in soybean (Glycine max).
View Article and Find Full Text PDFMicroscopy (Oxf)
January 2025
Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan.
Characterizing molten corium-concrete interaction (MCCI) fuel debris in Fukushima reactors is essential to develop efficient methods for its removal. To enhance the accuracy of microscopic observation and focused ion beam (FIB) microsampling of MCCI fuel debris, we developed a three-dimentional FIB scanning electron microscopy (SEM) technique with a multiphase positional misalignment (MPPM) correction method. This system automatically aligns voxel positions, corrects contrast, and removes artifacts from a series of over 500 SEM images.
View Article and Find Full Text PDFEnviron Res
January 2025
School of Creative Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo 169-8050, Japan; Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan. Electronic address:
Layered double hydroxides (LDHs) can effectively stabilize Se oxyanions, yet the thermal stability of Se oxyanions incorporated into LDHs remains unclear. In this study, calcination products of three types of LDHs loaded with SeO2- 3 or SeO2-4 were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray absorption fine structure spectroscopy (XAFS) and leaching tests. It has been found that SeO2-4 can be reduced to SeO2- 3 in the Fe-containing LDHs after calcination at temperatures above 450 °C.
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