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sulfur SAD phasing of Cdc23Nterm: data collection with a tailored X- ray beam size at 2.69 A wavelength (4.6 keV)
Structural highlights
FunctionAPC8_SCHPO Component of the anaphase-promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin-protein ligase complex that controls progression through mitosis and the G1 phase of the cell cycle. The APC/C is thought to confer substrate specificity and, in the presence of ubiquitin-conjugating E2 enzymes, it catalyzes the formation of protein-ubiquitin conjugates that are subsequently degraded by the 26S proteasome. Has a role in promoting metaphase to anaphase transition via the ubiquitination of specific mitotic substrates.[1] Publication Abstract from PubMedThe capability to reach wavelengths of up to 3.1 A at the newly established EMBL P13 beamline at PETRA III, the new third-generation synchrotron at DESY in Hamburg, provides the opportunity to explore very long wavelengths to harness the sulfur anomalous signal for phase determination. Data collection at lambda = 2.69 A (4.6 keV) allowed the crystal structure determination by sulfur SAD phasing of Cdc23(Nterm), a subunit of the multimeric anaphase-promoting complex (APC/C). At this energy, Cdc23(Nterm) has an expected Bijvoet ratio <|Fanom|>/<F> of 2.2%, with 282 residues, including six cysteines and five methionine residues, and two molecules in the asymmetric unit (65.4 kDa; 12 Cys and ten Met residues). Selectively illuminating two separate portions of the same crystal with an X-ray beam of 50 microm in diameter allowed crystal twinning to be overcome. The crystals diffracted to 3.1 A resolution, with unit-cell parameters a = b = 61.2, c = 151.5 A, and belonged to space group P43. The refined structure to 3.1 A resolution has an R factor of 18.7% and an Rfree of 25.9%. This paper reports the structure solution, related methods and a discussion of the instrumentation. Data collection with a tailored X-ray beam size at 2.69 A wavelength (4.6 keV): sulfur SAD phasing of Cdc23(Nterm).,Cianci M, Groves MR, Barford D, Schneider TR Acta Crystallogr D Struct Biol. 2016 Mar 1;72(Pt 3):403-12. doi:, 10.1107/S2059798315010268. Epub 2016 Mar 1. PMID:26960127[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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