8ENA

Thaumatin native-SAD structure determined at 5 keV with a helium environmet

Summary for 8ENA

• Entry DOI: 10.2210/pdb8ena/pdb
• Descriptor: Thaumatin-1 (2 entities in total)
• Functional Keywords: anomalous diffration, native sad, low energy, helium path, plant protein
• Biological source: Thaumatococcus daniellii
• Total number of polymer chains: 1
• Total formula weight: 22227.06

Authors

Karasawa, A.,Andi, B.,Ruchs, M.R.,Shi, W.,McSweeney, S.,Hendrickson, W.A.,Liu, Q. (deposition date: 2022-09-29, release date: 2022-11-02, Last modification date: 2024-05-01)

Primary citation

Karasawa, A.,Andi, B.,Fuchs, M.R.,Shi, W.,McSweeney, S.,Hendrickson, W.A.,Liu, Q.
Multi-crystal native-SAD phasing at 5 keV with a helium environment.
Iucrj, 9:768-777, 2022

PubMed Abstract: structure determination from single-wavelength anomalous diffraction using native sulfur or phospho-rus in biomolecules (native-SAD) is an appealing method to mitigate the labor-intensive production of heavy-atom derivatives and seleno-methio-nyl substitutions. The native-SAD method is particularly attractive for membrane proteins, which are difficult to produce and often recalcitrant to grow into decent-sized crystals. Native-SAD uses lower-energy X-rays to enhance anomalous signals from sulfur or phospho-rus. However, at lower energies, the scattering and absorption of air contribute to the background noise, reduce the signals and are thus adverse to native-SAD phasing. We have previously demonstrated native-SAD phasing at an energy of 5 keV in air at the NSLS-II FMX beamline. Here, the use of a helium path developed to reduce both the noise from background scattering and the air absorption of the diffracted X-ray beam are described. The helium path was used for collection of anomalous diffraction data at 5 keV for two proteins: thaumatin and the membrane protein TehA. Although anomalous signals from each individual crystal are very weak, robust anomalous signals are obtained from data assembled from micrometre-sized crystals. The thaumatin structure was determined from 15 microcrystals and the TehA structure from 18 microcrystals. These results demonstrate the usefulness of a helium environment in support of native-SAD phasing at 5 keV.

PubMed: 36381147
DOI: 10.1107/S205225252200971X

Experimental method

X-RAY DIFFRACTION (2.5 Å)