title: Structural basis for the PufX-mediated dimerization of bacterial photosynthetic core complexes.
abstract: In Rhodobacter (Rba.) sphaeroides, the subunit PufX is involved in the dimeric organization of the core complex. Here, we report the 3D reconstruction at 12 A by cryoelectron microscopy of the core complex of Rba. veldkampii, a complex of approximately 300 kDa without symmetry. The core complex is monomeric and constituted by a light-harvesting complex 1 (LH1) ring surrounding a uniquely oriented reaction center (RC). The LH1 consists of 15 resolved alpha/beta heterodimers and is interrupted. Within the opening, PufX polypeptide is assigned at a position facing the Q(B) site of the RC. This core complex is different from a dissociated dimer of the core complex of Rba. sphaeroides revealing that PufX in Rba. veldkampii is unable to dimerize. The absence in PufX of Rba. veldkampii of a G(31)XXXG(35) dimerization motif highlights the transmembrane interactions between PufX subunits involved in the dimerization of the core complexes of Rhodobacter species.
authors: Institut Curie, UMR-CNRS 168, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France.
authors: Johan
authors: J
authors: Busselez
authors: Magali
authors: M
authors: Cottevieille
authors: Philippe
authors: P
authors: Cuniasse
authors: Francesca
authors: F
authors: Gubellini
authors: Nicolas
authors: N
authors: Boisset
authors: Daniel
authors: D
authors: Lévy
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010788:Photosynthesis; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins