Crystallization, data collection and refinement of Lumazine Synthase from Brucella abortus bound to a substrate analogue inhibitor at 2.90 Å. (Poster)

SEBASTIÁN KLINKE; VANESA ZYLBERMAN; DANIEL R. VEGA; BEATRIZ G. GUIMARÃES; BRADFORD C. BRADEN; FERNANDO A.GOLDBAUM

Bariloche, Pcia. de Río Negro, Argentina

Congreso; XXXIX Reunión anual de SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular) y SAB (Sociedad Argentina de Biofísica), Bariloche Protein Symposium; 2003

SAIB y SAB

Lumazine synthase is an enzyme which catalyses the formation of 6,7-dimethyl-8-ribityllumazine, the penultimate product in the synthesis of riboflavin in Brucella abortus, the causative agent of brucellosis. It has been shown that this enzyme can bind several substrate and product analogues and even riboflavin. We cocrystallized lumazine synthase in the presence of the substrate analogue inhibitor 5-nitro-6-(D-ribitylamino)-2,4(1H,3H)-pyrimidinedione to yield diamond-like crystals which diffracted to a resolution of 2.90 Å and belong to the trigonal space group P3121. Initial phasing was carried out applying Molecular Replacement procedures using previously known free lumazine synthase as model. We obtained one molecule per crystal asymmetric unit with a solvent content of ca. 70%. First Fourier difference maps built showed a strong electronic density near the active site of the enzyme, which corresponded to the bound substrate analogue. Refinement of the crystallographic structure is being performed to describe the protein-ligand interaction. Preliminary analysis showed a strong hydrophobic stacking between the substrate analogue and residues Trp22 and Pro8.