X-ray structure of a putative reaction intermediate of 5-aminolaevulinic acid dehydratase.
The X-ray structure of yeast 5-aminolaevulinic acid dehydratase, in which the catalytic site of the enzyme is complexed with a putative cyclic intermediate composed of both substrate moieties, has been solved at 0.16 nm (1.6 A) resolution. The cyclic intermediate is bound covalently to Lys(263) with the amino group of the aminomethyl side chain ligated to the active-site zinc ion in a position normally occupied by a catalytic hydroxide ion. The cyclic intermediate is catalytically competent, as shown by its turnover in the presence of added substrate to form porphobilinogen. The findings, combined with those of previous studies, are consistent with a catalytic mechanism in which the C-C bond linking both substrates in the intermediate is formed before the C-N bond.
Erskine
Peter T
PT
Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK.
Coates
Leighton
L
Butler
Danica
D
Youell
James H
JH
Brindley
Amanda A
AA
Wood
Steve P
SP
Warren
Martin J
MJ
Shoolingin-Jordan
Peter M
PM
Cooper
Jonathan B
JB
D018360:Crystallography, X-Ray; D008958:Models, Molecular; D000623:Porphobilinogen Synthase / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D011994:Recombinant Proteins; D000623:Porphobilinogen Synthase