| 1. |
- Duan, Ming-Rui, et al.
(författare)
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DNA binding mechanism revealed by high resolution crystal structure of Arabidopsis thaliana WRKY1 protein
- 2007
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 35:4, s. 54-1145
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Tidskriftsartikel (refereegranskat)abstract
- WRKY proteins, defined by the conserved WRKYGQK sequence, are comprised of a large superfamily of transcription factors identified specifically from the plant kingdom. This superfamily plays important roles in plant disease resistance, abiotic stress, senescence as well as in some developmental processes. In this study, the Arabidopsis WRKY1 was shown to be involved in the salicylic acid signaling pathway and partially dependent on NPR1; a C-terminal domain of WRKY1, AtWRKY1-C, was constructed for structural studies. Previous investigations showed that DNA binding of the WRKY proteins was localized at the WRKY domains and these domains may define novel zinc-binding motifs. The crystal structure of the AtWRKY1-C determined at 1.6 A resolution has revealed that this domain is composed of a globular structure with five beta strands, forming an antiparallel beta-sheet. A novel zinc-binding site is situated at one end of the beta-sheet, between strands beta4 and beta5. Based on this high-resolution crystal structure and site-directed mutagenesis, we have defined and confirmed that the DNA-binding residues of AtWRKY1-C are located at beta2 and beta3 strands. These results provided us with structural information to understand the mechanism of transcriptional control and signal transduction events of the WRKY proteins.
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| 2. |
- Zhao-Hai, He, et al.
(författare)
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Characters of the magnetotail plasma injection surveyed from Cluster observation
- 2008
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Ingår i: Chinese Journal of Geophysics. - 0001-5733. ; 51:2, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- The properties of proton (0 eV < E < 40 keV) in the plasma sheet are examined by means of a superposed epoch analysis, using 115 magnetotail plasma injection events which are identified from Cluster magnetotail orbit time in between 2001 and 2004. All events distribute in magnetic local time from 20 p.m. to 04 a. in. Five classes of magnetotail injection events are found to be similar with the geosynchronous observation: (1) pure ion injections; (2) ion injections followed a few minutes later by an electron injection; (3) simultaneous ion and electron injections; (4) electron injections followed a few minutes later by an ion injection; (5) pure electron injections. Proton shows a significant increase in temperature and density at the onset, and injects earthward with an increasing velocity more than the pre-injection average one. Super-posed epoch analysis on the simultaneous observation data of dusk-dawn electric field from the EFW (Electric Field and Waves) instrument, we found two different electric field configurations: ( I) electric field increases suddenly at the onset and the value is positive; (2) electric field changes the direction at the onset, and turns into a negative value. The simulation results of velocity vector after injection in equatorial plain, calculated in static magnetic (T89c) and electric (Volland-Stern) field models, agree with the statistical results mostly, and that suggests the electric drift caused by dawn-dusk convection electric field is one of the mechanisms of the particles injected earthward in magnetotail(-18 R-E < R < -10R(E)).
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