Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2829601 | Journal of Structural Biology | 2006 | 6 Pages |
Abstract
Phytochromes are photochromic photoreceptors with a bilin chromophore that have been found in plants and bacteria. Typical bacterial phytochromes are composed of an N-terminal photosensory chromophore module and a C-terminal protein kinase. The former contains the chromophore, which allows phytochromes to adopt the two interconvertible spectral forms, Pr and Pfr. The N-terminal photosensory module of Agrobacterium phytochrome Agp1, Agp1-M15, was used for crystallization studies. The protein was either assembled with the natural chromophore biliverdin or a sterically locked synthetic biliverdin-derivative, termed 15Za. The last-named adduct does not undergo photoisomerization due to an additional carbon chain between the rings C and D of the chromophore. Both adducts could be crystallized, but the resolution was largely improved by the use of 15Za. Crystals of biliverdin-Agp1-M15 diffract to 6Â Ã
resolution and belong to the tetragonal space group I422 with unit cell dimensions a = b = 171 Ã
, c = 81 Ã
, crystals of 15Za-Agp1-M15 belong to the same space group with similar unit cell dimensions a = b = 174 Ã
, c = 80 Ã
, but diffract to 3.4Â Ã
resolution. Assuming the asymmetric unit to be occupied by one monomer of 55Â kDa, the unit cell contains 54-55% solvent with a crystal volume per protein mass, Vm, of 2.7Â Ã
3 Daâ1.
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Authors
Patrick Scheerer, Norbert Michael, Jung Hee Park, Steffi Noack, Charlotte Förster, Mostafa A.S. Hammam, Katsuhiko Inomata, Hui-Woog Choe, Tilman Lamparter, Norbert KrauÃ,