Binding Isotope Effects for para-Aminobenzoic Acid with Dihydropteroate Synthase from Staphylococcus aureus and Plasmodium falciparum.
Dihydropteroate synthase is a key enzyme in folate biosynthesis and is the target of the sulfonamide class of antimicrobials. Equilibrium binding isotope effects and density functional theory calculations indicate that the substrate binding sites for para-aminobenzoic acid on the dihydropteroate synthase enzymes from Staphylococcus aureus and Plasmodium falciparum present distinct chemical environments. Specifically, we show that para-aminobenzoic acid occupies a more sterically constrained vibrational environment when bound to dihydropteroate synthase from P. falciparum relative to that of S. aureus. Deletion of a nonhomologous, parasite-specific insert from the plasmodial dihydropteroate synthase abrogated the binding of para-aminobenzoic acid. The loop specific to P. falciparum is important for effective substrate binding and therefore plays a role in modulating the chemical environment at the substrate binding site.
Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States.
Christopher F
CF
Stratton
Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States.
Hilda A
HA
Namanja-Magliano
Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States.
Scott A
SA
Cameron
Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States.
Vern L
VL
Schramm
D010129:4-Aminobenzoic Acid / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D004094:Dihydropteroate Synthase / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D007554:Isotopes / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010963:Plasmodium falciparum / Q000201:enzymology*; D016415:Sequence Alignment; D013211:Staphylococcus aureus / Q000201:enzymology*
D007554:Isotopes; D006859:Hydrogen; D004094:Dihydropteroate Synthase; D010129:4-Aminobenzoic Acid