High-resolution structure of a papaya plant-defence barwin-like protein solved by in-house sulfur-SAD phasing.Huet, J., Teinkela Mbosso, E.J., Soror, S., Meyer, F., Looze, Y., Wintjens, R., Wohlkonig, A.
(2013) Acta Crystallogr.,Sect.D 69: 2017-2026
- PubMed: 24100320
- DOI: 10.1107/S0907444913018015
- Primary Citation of Related Structures:
- PubMed Abstract:
The first crystal structure of a barwin-like protein, named carwin, has been determined at high resolution by single-wavelength anomalous diffraction (SAD) phasing using the six intrinsic S atoms present in the protein. The barwin-like protein was pu ...
The first crystal structure of a barwin-like protein, named carwin, has been determined at high resolution by single-wavelength anomalous diffraction (SAD) phasing using the six intrinsic S atoms present in the protein. The barwin-like protein was purified from Carica papaya latex and crystallized in the orthorhombic space group P212121. Using in-house Cu Kα X-ray radiation, 16 cumulative diffraction data sets were acquired to increase the signal-to-noise level and thereby the anomalous scattering signal. A sequence-database search on the papaya genome identified two carwin isoforms of 122 residues in length, both containing six S atoms that yield an estimated Bijvoet ratio of 0.93% at 1.54 Å wavelength. A systematic analysis of data quality and redundancy was performed to assess the capacity to locate the S atoms and to phase the data. It was observed that the crystal decay was low during data collection and that successful S-SAD phasing could be obtained with a relatively low data multiplicity of about 7. Using a synchrotron source, high-resolution data (1 Å) were collected from two different crystal forms of the papaya latex carwin. The refined structures showed a central β-barrel of six strands surrounded by several α-helices and loops. The β-barrel of carwin appears to be a common structural module that is shared within several other unrelated proteins. Finally, the possible biological function of the protein is discussed.
Laboratoire des Biopolymères et des Nanomatériaux Supramoléculaires (CP206/04), Faculté de Pharmacie, Université Libre de Bruxelles, B-1050 Brussels, Belgium.