Towards the understanding of the function of Rb sphaeroides Y wild type reaction center: gene cloning, protein and detergent structures in the three-dimensional crystals.
We report various experiments aimed at the resolution of the 3-dimensional structure of the photosynthetic reaction center from wild type Y Rhodobacter sphaeroides. The genes encoding the L and M polypeptides have been cloned and sequenced. They bear 2 mutations each when compared to those already sequenced in another Rb sphaeroides strain (2.4.1). In the L gene, these codon changes are silent. In the M gene, one is silent and the other one leads to a Leu-Met substitution at position 140. At the present stage of the refinement of the X-ray data (0.3 nm resolution) the structure of the Y reaction center is shown to be highly similar to that of the Rhodopseudomonas viridis reaction center. The binding of spheroidene on the M side of the Y reaction center is shown to be determined by hydrophobic interactions with neighboring amino acids and by steric factors. Preliminary results concerning the localization of the detergent (beta-octylglucoside) in the unit cell are presented. This method combines low angle neutron scattering at different contrasts in H2O/D2O with X-ray crystallographic data.
Arnoux
B
B
Laboratoire de Cristallochimie, ICSN-CNRS, Gif-sur-Yvette, France.
Ducruix
A
A
Astier
C
C
Picaud
M
M
Roth
M
M
Reiss-Husson
F
F
D002338:Carotenoids / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D003902:Detergents; D005798:Genes, Bacterial; D005960:Glucosides / Q000737:chemistry*; D009154:Mutation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics*; D011487:Protein Conformation; D015183:Restriction Mapping; D012242:Rhodobacter sphaeroides / Q000235:genetics*; D013237:Stereoisomerism; D014961:X-Ray Diffraction
D003902:Detergents; D005960:Glucosides; D045322:Photosynthetic Reaction Center Complex Proteins; C018619:octyl-beta-D-glucoside; D002338:Carotenoids