title: The X-ray structure of yeast 5-aminolaevulinic acid dehydratase complexed with two diacid inhibitors.
abstract: The structures of 5-aminolaevulinic acid dehydratase complexed with two irreversible inhibitors (4-oxosebacic acid and 4,7-dioxosebacic acid) have been solved at high resolution. Both inhibitors bind by forming a Schiff base link with Lys 263 at the active site. Previous inhibitor binding studies have defined the interactions made by only one of the two substrate moieties (P-side substrate) which bind to the enzyme during catalysis. The structures reported here provide an improved definition of the interactions made by both of the substrate molecules (A- and P-side substrates). The most intriguing result is the novel finding that 4,7-dioxosebacic acid forms a second Schiff base with the enzyme involving Lys 210. It has been known for many years that P-side substrate forms a Schiff base (with Lys 263) but until now there has been no evidence that binding of A-side substrate involves formation of a Schiff base with the enzyme. A catalytic mechanism involving substrate linked to the enzyme through Schiff bases at both the A- and P-sites is proposed.
authors.affiliation: Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, UK.
authors.forename: P T
authors.initials: PT
authors.lastname: Erskine
authors.forename: L
authors.initials: L
authors.lastname: Coates
authors.forename: R
authors.initials: R
authors.lastname: Newbold
authors.forename: A A
authors.initials: AA
authors.lastname: Brindley
authors.forename: F
authors.initials: F
authors.lastname: Stauffer
authors.forename: S P
authors.initials: SP
authors.lastname: Wood
authors.forename: M J
authors.initials: MJ
authors.lastname: Warren
authors.forename: J B
authors.initials: JB
authors.lastname: Cooper
authors.forename: P M
authors.initials: PM
authors.lastname: Shoolingin-Jordan
authors.forename: R
authors.initials: R
authors.lastname: Neier
mesh_terms: D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003652:Decanoic Acids / Q000737:chemistry / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000737:chemistry; D046911:Macromolecular Substances; D008958:Models, Molecular; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012545:Schiff Bases / Q000737:chemistry; D055672:Static Electricity; D013379:Substrate Specificity
chemical_list: C434703:4,7-dioxosebacic acid; C434705:4-oxosebacic acid; D003652:Decanoic Acids; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D012545:Schiff Bases; D000623:Porphobilinogen Synthase