Structures of Ligand-free and Inhibitor Complexes of Dihydroorotase from Escherichia coli: Implications for Loop Movement in Inhibitor Design

Abstract

Dihydroorotase (DHOase) catalyzes the reversible cyclization of N-carbamyl-l-aspartate (CA-asp) to l-dihydroorotate (DHO) in the de novo biosynthesis of pyrimidine nucleotides. DHOase is a potential anti-malarial drug target as malarial parasites can only synthesize pyrimidines via the de novo pathway and do not possess a salvage pathway. Here we report the structures of Escherichia coli DHOase crystallized without ligand (1.7 Å resolution) and in the presence of the inhibitors 2-oxo-1,2,3,6-tetrahydropyrimidine-4,6-dicarboxylate (HDDP; 2.0 Å) and 5-fluoroorotate (FOA, 2.2 Å). These are the first crystal structures of DHOase-inhibitor complexes, providing structural information on the mode o..