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Dimerization properties of the RpBphP2 chromophore-binding domain crystallized by homologue-directed mutagenesis.
- Source :
-
Acta crystallographica. Section D, Biological crystallography [Acta Crystallogr D Biol Crystallogr] 2012 Aug; Vol. 68 (Pt 8), pp. 1058-66. Date of Electronic Publication: 2012 Jul 17. - Publication Year :
- 2012
-
Abstract
- Bacteriophytochromes (BphPs) are biliverdin IXα-containing photoreceptors that photoconvert between red (Pr) and far-red (Pfr) absorbing states. BphPs are one half of a two-component system that transmits a light signal to a histidine kinase domain and then to a gene-response regulator. In Rhodopseudomonas palustris, synthesis of a light-harvesting complex (LH4) is controlled by two BphPs (RpBphP2 and RpBphP3). Despite their high sequence identity (52%), their absorption spectra are very different. The spectra of RpBphP2 exhibit classic Pr-to-Pfr photoconversion, whereas RpBphP3 quenches and a high-energy Pnr state emerges [Giraud et al. (2005), J. Biol. Chem. 280, 32389-32397]. Crystallization of the chromophore-binding domain (CBD) of RpBphP2 (RpBphP2-CBD) proved to be difficult and the structure of RpBphP3-CBD was used to crystallize RpBphP2-CBD* using homologue-directed mutagenesis. The structure shows that dimerization is an important factor in successful crystallization of RpBphP2-CBD* and arises from an N136R mutation. Mutations at this site correlate with an ability to dimerize in other truncated BphPs and may also be important for full-length dimer formation. Comparison of the RpBphP3-CBD and RpBphP2-CBD* biliverdin IXα pockets revealed that the former has additional hydrogen bonding around the B and D pyrrole rings that may constrain photoconversion to Pfr, resulting in a strained photoexcited Pnr state.
- Subjects :
- Chromatography, Gel
Cloning, Molecular
Crystallization
Crystallography, X-Ray methods
Dimerization
Models, Chemical
Molecular Conformation
Mutagenesis
Mutation
Protein Structure, Tertiary
Rhodopseudomonas metabolism
Spectrophotometry, Ultraviolet methods
Bacterial Proteins chemistry
Chromatophores chemistry
Light-Harvesting Protein Complexes chemistry
Phytochrome chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1399-0047
- Volume :
- 68
- Issue :
- Pt 8
- Database :
- MEDLINE
- Journal :
- Acta crystallographica. Section D, Biological crystallography
- Publication Type :
- Academic Journal
- Accession number :
- 22868772
- Full Text :
- https://doi.org/10.1107/S0907444912020537