Structure d'oligodesoxynucleotides contenant des sites abasiques par resonance magnetique nucleaire

SIGLEINIST T 70806 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Structural Basis for the PufX-Mediated Dimerization of Bacterial Photosynthetic Core Complexes

International audienceIn 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

Structural Basis of Antibody Cross-Reactivity: Solution Conformation of an Immunogenic Peptide Fragment Containing both T and B Epitopes

International audienc

Identification of two-histidines one-carboxylate binding motifs in proteins amenable to facial coordination to metals

Among natural metalloenzymes, the facial two-histidines one-carboxylate binding motif (FTM) is a widely represented first coordination sphere motif present in the active site of a variety of metalloenzymes. A PDB search revealed a total of 1685 structures bearing such FTMs bound to a metal. Sixty statistically representative FTMs were selected and used as template for the identification of structurally characterized proteins bearing these three amino acids in a propitious environment for binding to a transition metal. This geometrical superposition search, carried out using the STAMPS software, returned 2320 hits. While most consisted of either apo-FTMs or bore strong sequence homology to known FTMs, seven such structures lying within a cavity were identified as novel and viable scaffolds for the creation of artificial metalloenzymes bearing an FTM