Busselez Johan, Cottevieille Magali, Cuniasse Philippe, Gubellini Francesca, Boisset Nicolas, Lévy Daniel
Institut Curie, UMR-CNRS 168, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France.
Structure. 2007 Dec;15(12):1674-83. doi: 10.1016/j.str.2007.09.026.
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.
在球形红杆菌（Rba. sphaeroides）中，亚基PufX参与核心复合物的二聚体组织。在此，我们通过冷冻电子显微镜报告了维氏红杆菌（Rba. veldkampii）核心复合物在12埃分辨率下的三维重建，该复合物约300 kDa且无对称性。核心复合物是单体，由围绕独特取向的反应中心（RC）的捕光复合物1（LH1）环构成。LH1由15个可分辨的α/β异二聚体组成且有中断。在开口处，PufX多肽位于面向RC的Q(B)位点的位置。该核心复合物不同于球形红杆菌核心复合物的解离二聚体，这表明维氏红杆菌中的PufX无法二聚化。维氏红杆菌的PufX中缺乏G(31)XXXG(35)二聚化基序，这突出了参与红杆菌属物种核心复合物二聚化的PufX亚基之间的跨膜相互作用。
