TY - JOUR TI - 3.3-Å resolution cryo-EM structure of human ribonucleotide reductase with substrate and allosteric regulators bound AU - Brignole, Edward J AU - Tsai, Kuang-Lei AU - Chittuluru, Johnathan AU - Li, Haoran AU - Aye, Yimon AU - Penczek, Pawel A AU - Stubbe, JoAnne AU - Drennan, Catherine L AU - Asturias, Francisco A2 - Kuriyan, John VL - 7 PY - 2018 DA - 2018/02/20 SP - e31502 C1 - eLife 2018;7:e31502 DO - 10.7554/eLife.31502 UR - https://doi.org/10.7554/eLife.31502 AB - Ribonucleotide reductases (RNRs) convert ribonucleotides into deoxyribonucleotides, a reaction essential for DNA replication and repair. Human RNR requires two subunits for activity, the α subunit contains the active site, and the β subunit houses the radical cofactor. Here, we present a 3.3-Å resolution structure by cryo-electron microscopy (EM) of a dATP-inhibited state of human RNR. This structure, which was determined in the presence of substrate CDP and allosteric regulators ATP and dATP, has three α2 units arranged in an α6 ring. At near-atomic resolution, these data provide insight into the molecular basis for CDP recognition by allosteric specificity effectors dATP/ATP. Additionally, we present lower-resolution EM structures of human α6 in the presence of both the anticancer drug clofarabine triphosphate and β2. Together, these structures support a model for RNR inhibition in which β2 is excluded from binding in a radical transfer competent position when α exists as a stable hexamer. KW - single-particle electron microscopy KW - protein structure KW - chemotherapeutic target KW - nucleic acid metabolism KW - radical mechanism KW - allosteric regulation JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -