title: Probing the active site of Pseudomonas aeruginosa porphobilinogen synthase using newly developed inhibitors.
abstract: Porphobilinogen synthase catalyzes the first committed step of the tetrapyrrole biosynthesis pathway. In an aldol-like condensation, two molecules of 5-aminolevulinic acid (ALA) form the first pyrrole, porphobilinogen. Newly synthesized analogues of a reaction intermediate of porphobilinogen synthase have been employed in studying the active site and the catalytic mechanism of this early enzyme of tetrapyrrole biosynthesis. This study combines structural and kinetic evaluation of the inhibition potency of these inhibitors. In addition, one of the determined protein structures provides for the first time structural evidence of a magnesium ion in the active site. From these results, we can corroborate an earlier postulated enzymatic mechanism that starts with formation of a C-C bond, linking C3 of the A-side ALA to C4 of the P-side ALA through an aldole addition. The obtained data are discussed with respect to the current literature.
authors.affiliation: Institute for Microbiology, Technical University Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany.
authors.forename: Frederic
authors.initials: F
authors.lastname: Frère
authors.forename: Merle
authors.initials: M
authors.lastname: Nentwich
authors.forename: Sabine
authors.initials: S
authors.lastname: Gacond
authors.forename: Dirk W
authors.initials: DW
authors.lastname: Heinz
authors.forename: Reinhard
authors.initials: R
authors.lastname: Neier
authors.forename: Nicole
authors.initials: N
authors.lastname: Frankenberg-Dinkel
mesh_terms: D001665:Binding Sites; D002384:Catalysis / Q000187:drug effects; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry*; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D000623:Porphobilinogen Synthase; D008274:Magnesium