The X-ray structure of yeast 5-aminolaevulinic acid dehydratase complexed with two diacid inhibitors.
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.
Erskine
P T
PT
Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, UK.
Coates
L
L
Newbold
R
R
Brindley
A A
AA
Stauffer
F
F
Wood
S P
SP
Warren
M J
MJ
Cooper
J B
JB
Shoolingin-Jordan
P M
PM
Neier
R
R
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
C434703:4,7-dioxosebacic acid; C434705:4-oxosebacic acid; D003652:Decanoic Acids; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D012545:Schiff Bases; D000623:Porphobilinogen Synthase