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Science
and Technology
Day 2012
Poster
Exhibition
Department
of Chemical
and Biological
Engineering
Chalmers
University
of Technology
Department
of Chemistry
and Molecular
Biology
University
of Gothenburg
March 27th 2012
Process and ProductionFundamental
Aspects
and
Modeling
C28. PREDICTION OF THE THREE.DIMENSIONAL STRUCTURE OF THE PLANT UVRS PHOTORECEPTOR DIMER, AND THE KEY
RESIDUES IN UV.B REGULATED SIGNALLING PATHWAY Min Wua, Ake Stridb and Leif A. Erikssona
aSchool of Chemistry and Molecular Biology, lJniversity of Gothenburg,
SE-41296, Gdteborg, Sweden
bschoot of Science and Technotogy, Orebro lJniversity, SE-70182 6rebro, Sweden
min.wu@chem.gu.se Life. Health and Food Science
The dimeric UVR8 protein is a ultraviolet-B radiation (280-315 nm) photoreceptor that is responsible for the first step in UV-B regulation of gene expression in plantsr. Its action comprises the actual absorption of the UV quanta by a Trp array in the protein, f6llowed by monomerisation, and subsequent aggregation with downstream signaling components2. A computationally predicted structure of the Arabidopsis thaliana tryptophan-rich UVR8 protein dimer, comprising a total of 140.000 atoms is here presented. Quantum chemical calculations of excitation spectra of both a large cluster model involving seven tryptophans at the interface of the UVR8 protein where they are intermixed with positive residues (mainly arginines) and a couple of tyrosines, and smaller fragments thereof, reveal that absorption maxima appearing in the 280-300 nm range for the full cluster result from interactions between the central tryptophans and surrounding arginines. This observation provides an explanation for the experimentally measured action spectrum of the UVR8-dependent UV-B stimulation of HY5 transcription in mature A. thaliana leaftissue2.
References.
[1] Brown BA, Cloxi C, Jiang GH, Kaiserli E, Herzyk P, Kliebenstein DJ, Jenkins Gt..2005. A UV-B-specific singaling component orchestrates plant UV protection. Proc. Natl.Acad.sci.usA 102:18225-3 0 .
[2] Rizzini L, Favory JJ, Cloix C, Faggionato D, Hara AO, Kaiserli E, Baumeister R, Schiifer E, Nagy F, J e n k i n s G l , u l m R . 2 0 1 1 . P e r c e p t i o n o f u v - B b y t h e A r a b i d o p s i s u v R S p r o t e i n . s c l e n c e 3 3 2 : 1 0 3 - ' 1 0 7 .
