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A structural biology technique that flash-freezes biomolecules and images them with electrons to reveal near-atomic 3D structures of proteins and complexes.
University of Arkansas researchers used cryo-EM to show a methanogen stops fixing nitrogen by binding its enzyme into an inactive supercomplex. The structure, in Nature, pinpoints the regulatory contact a bioengineer would have to control.
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Six PII complexes hold three units of a methanogen's nitrogenase inactive in the first archaeal nitrogenase structure, solved by cryo-EM. ATP and 2-oxoglutarate free the enzyme and triple its activity in vitro, a switch living cells have yet to confirm.
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Structures in Nature catch human spliceosomes at two stages of termination as three helicases and the enzyme DBR1 free and debranch the spent intron. How the machine is cleared for its next round, and its intron sent to decay, had been an open question.
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Researchers reporting in Nature used cryo-EM to resolve 76 coexisting active and inactive conformers of a bacterial RNase P RNA. They argue that the enzyme's activity depends on how this population of shapes moves together with its bound magnesium ions.
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NTU scientists built a compound that starves Mycobacterium abscessus of energy; paired with the drug clofazimine it cut the microbe a hundredfold in four days. Two other teams mapped the same bacterium's virus defenses and a related pathogen's toxin-firing weapon.
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Researchers report that graphene reservoirs confine sub-100-nm liquid films for cryo-EM, so ice thickness can be tuned by reservoir depth. They trace decades of trial-and-error ice preparation to thin films that drain and rupture on their own before anything freezes.
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Crick researchers report that two four-subunit RAD51 paralog complexes assemble and cap DNA repair filaments, after about 20 years of stalled study. The genes sit in the BRCA pathway and the structures may help explain disease mutations, but the work includes no drug or patient data.
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A Max Delbrück Center team froze rabbit sarcoplasmic reticulum with the channels still in the bilayer and caught six opening states, giving coupled gating a structural account almost 30 years after it was described.
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Weill Cornell biophysicists used cryo-EM to map the pocket where trace amounts of the lipid PIP2 dock onto rod-cell CNG channels and hold them shut. The site is a candidate drug target for inherited retinal degeneration, so far studied only in synthetic membranes.
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A nine-amino-acid peptide assembles into hexagonal pores and tiles them into a honeycomb lattice, with water-accessible channels about 5 nanometres wide. Cryo-EM found the same pore geometry in every variant.
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A team at HIPS, the Institut Pasteur and Universite Paris Cite reports that corramycin attacks the same enzyme as fluoroquinolones by a different route and stays active against isolates those drugs no longer touch. An earlier program dropped the compound over production cost.
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Liege and Rockefeller researchers report near-atomic structures of the machine that adds the same short leader to nearly every trypanosomatid messenger RNA, including several proteins with no human counterpart.
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Two Johns Hopkins papers in Nature Communications examined double-strand breaks in DNA still wound on histones. The repair machinery joined the broken ends without stripping that packaging off first.
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Researchers at Cambridge and the MRC Laboratory of Molecular Biology report in Nature that the enzyme RNF213 ubiquitylates poorly branched glycogen directly, and that mice without that ligase activity accumulate polyglucosan in three brain regions.
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The four-unit protein can come apart directly when conditions turn acidic, and a screen of more than 100 variants suggests some brain-amyloidosis mutations reach that route at normal blood pH. Whether tafamidis blocks it was not tested.
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The enzyme that loads methionine onto tRNA in this cell-invading bacterium is twice the size of the E. coli version. Rebecca Alexander's lab at Wake Forest reports that the extra half looks like a second enzyme.
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A Penn State team pulled native RNA polymerase II complexes out of fruit fly embryos and found some missing two of the canonical 12 subunits. The purified picture was tidier than the cell.
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