6i59
From Proteopedia
Long wavelength native-SAD phasing of Sen1 helicase
Structural highlights
Function[SEN1_YEAST] ATP-dependent 5'->3' DNA/RNA helicase required for the expression and maturation of diverse classes of non-protein-coding RNAs like precursor tRNAs, rRNAs and small nuclear (snRNA) and nucleolar (snoRNA) RNAs. Directs RNA polymerase II transcription termination on snoRNAs as well as on several short protein-coding genes. May also play a role in transcription-coupled nucleotide excision repair.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedNative single-wavelength anomalous dispersion (SAD) is an attractive experimental phasing technique as it exploits weak anomalous signals from intrinsic light scatterers (Z < 20). The anomalous signal of sulfur in particular, is enhanced at long wavelengths, however the absorption of diffracted X-rays owing to the crystal, the sample support and air affects the recorded intensities. Thereby, the optimal measurable anomalous signals primarily depend on the counterplay of the absorption and the anomalous scattering factor at a given X-ray wavelength. Here, the benefit of using a wavelength of 2.7 over 1.9 A is demonstrated for native-SAD phasing on a 266 kDa multiprotein-ligand tubulin complex (T2R-TTL) and is applied in the structure determination of an 86 kDa helicase Sen1 protein at beamline BL-1A of the KEK Photon Factory, Japan. Furthermore, X-ray absorption at long wavelengths was controlled by shaping a lysozyme crystal into spheres of defined thicknesses using a deep-UV laser, and a systematic comparison between wavelengths of 2.7 and 3.3 A is reported for native SAD. The potential of laser-shaping technology and other challenges for an optimized native-SAD experiment at wavelengths >3 A are discussed. Long-wavelength native-SAD phasing: opportunities and challenges.,Basu S, Olieric V, Leonarski F, Matsugaki N, Kawano Y, Takashi T, Huang CY, Yamada Y, Vera L, Olieric N, Basquin J, Wojdyla JA, Bunk O, Diederichs K, Yamamoto M, Wang M IUCrJ. 2019 Apr 1;6(Pt 3):373-386. doi: 10.1107/S2052252519002756. eCollection, 2019 May 1. PMID:31098019[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Baker's yeast | Large Structures | Basquin, J | Basu, S | Bunk, O | Diederichs, K | Huang, C Y | Kawano, Y | Leonarski, F | Matsugaki, N | Olieric, N | Olieric, V | Takashi, T | Vera, L | Wang, M | Wojdyla, J A | Yamada, Y | Yamamoto, M | Dna binding protein | Long-wavelength native-sad phasing | Native-sad | S-sad | Sen1 helicase | Super family 1b
