title: Crystal structure of 7,8-dihydropteroate synthase from Bacillus anthracis: mechanism and novel inhibitor design.
abstract: Dihydropterate synthase (DHPS) is the target for the sulfonamide class of antibiotics, but increasing resistance has encouraged the development of new therapeutic agents against this enzyme. One approach is to identify molecules that occupy the pterin binding pocket which is distinct from the pABA binding pocket that binds sulfonamides. Toward this goal, we present five crystal structures of DHPS from Bacillus anthracis, a well-documented bioterrorism agent. Three DHPS structures are already known, but our B. anthracis structures provide new insights into the enzyme mechanism. We show how an arginine side chain mimics the pterin ring in binding within the pterin binding pocket. The structures of two substrate analog complexes and the first structure of a DHPS-product complex offer new insights into the catalytic mechanism and the architecture of the pABA binding pocket. Finally, as an initial step in the development of pterin-based inhibitors, we present the structure of DHPS complexed with 5-nitro-6-methylamino-isocytosine.
authors.affiliation: Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: Kerim
authors.initials: K
authors.lastname: Babaoglu
authors.forename: Jianjun
authors.initials: J
authors.lastname: Qi
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lee
authors.forename: Stephen W
authors.initials: SW
authors.lastname: White
mesh_terms: D000595:Amino Acid Sequence; D001408:Bacillus anthracis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D023482:Bioterrorism; D018360:Crystallography, X-Ray; D004094:Dihydropteroate Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011622:Pterins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D011622:Pterins; C005584:pteroic acid; D004094:Dihydropteroate Synthase