title: Structural basis for competitive inhibition of 3,4-dihydroxy-2-butanone-4-phosphate synthase from Vibrio cholerae.
abstract: The riboflavin biosynthesis pathway has been shown to be essential in many pathogens and is absent in humans. Therefore, enzymes involved in riboflavin synthesis are considered as potential antibacterial drug targets. The enzyme 3,4-dihydroxy-2-butanone-4-phosphate synthase (DHBPS) catalyzes one of the two committed steps in the riboflavin pathway and converts d-ribulose 5-phosphate (Ru5P) to l-3,4-dihydroxy-2-butanone 4-phosphate and formate. Moreover, DHBPS is shown to be indispensable for Mycobacterium, Salmonella, and Helicobacter species. Despite the essentiality of this enzyme in bacteria, no inhibitor has been identified hitherto. Here, we describe kinetic and crystal structure characterization of DHBPS from Vibrio cholerae (vDHBPS) with a competitive inhibitor 4-phospho-d-erythronohydroxamic acid (4PEH) at 1.86-Å resolution. In addition, we also report the structural characterization of vDHBPS in its apo form and in complex with its substrate and substrate plus metal ions at 1.96-, 1.59-, and 2.04-Å resolution, respectively. Comparison of these crystal structures suggests that 4PEH inhibits the catalytic activity of DHBPS as it is unable to form a proposed intermediate that is crucial for DHBPS activity. Furthermore, vDHBPS structures complexed with substrate and metal ions reveal that, unlike Candida albicans, binding of substrate to vDHBPS induces a conformational change from an open to closed conformation. Interestingly, the position of second metal ion, which is different from that of Methanococcus jannaschii, strongly supports an active role in the catalytic mechanism. Thus, the kinetic and structural characterization of vDHBPS reveals the molecular mechanism of inhibition shown by 4PEH and that it can be explored further for designing novel antibiotics.
authors: From the CSIR-Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160 036, India and.
authors: Zeyaul
authors: Z
authors: Islam
authors: From the CSIR-Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160 036, India and.
authors: Adarsh
authors: A
authors: Kumar
authors: From the CSIR-Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160 036, India and.
authors: Suruchi
authors: S
authors: Singh
authors: Laboratoire de Chimie Bioorganique et Bioinorganique, Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Sud, CNRS UMR8182, F-91405 Orsay, France.
authors: Laurent
authors: L
authors: Salmon
authors: From the CSIR-Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160 036, India and skarthik@imtech.res.in.
authors: Subramanian
authors: S
authors: Karthikeyan
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D006877:Hydroxamic Acids / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008025:Ligases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012256:Riboflavin / Q000096:biosynthesis; D013403:Sugar Phosphates / Q000378:metabolism* / Q000494:pharmacology*; D014734:Vibrio cholerae / Q000201:enzymology*
chemical_list: C518606:4-phosphoerythronohydroxamic acid; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D013403:Sugar Phosphates; C066494:3,4-dihydroxy-2-butanone-4-phosphate; D008025:Ligases; D012256:Riboflavin
keywords: Crystal Structure; DHBPS; Enzyme Inhibitor; Enzyme Kinetics; Enzyme Mechanism; Riboflavin; Ribulose 5-Phosphate; ribB