5-Aminolaevulinic acid dehydratase catalyses the formation of porphobilinogen from two molecules of 5-aminolaevulinic acid. The studies described highlight the importance of a bivalent metal ion and two active-site lysine residues for the functioning of 5-aminolaevulinic acid dehydratase. Dehydratases fall into two main categories: zinc-dependent enzymes and magnesium-dependent enzymes. Mutations that introduced zinc-binding ligands into a magnesium-dependent enzyme conferred an absolute requirement for zinc. Mutagenesis of lysine residues 247 and 195 in the Escherichia coli enzyme lead to dramatic effects on enzyme activity, with lysine 247 being absolutely essential. Mutation of either lysine 247 or 195 to cysteine, and treatment of the mutant enzyme with 2-bromethylamine, resulted in the recovery of substantial enzyme activity. The effects of the site-directed alkylating inhibitor, 5-chlorolaevulinic acid, and 4,7-dioxosebacic acid, a putative intermediate analogue, were investigated by X-ray crystallography. These inhibitors reacted with both active-site lysine residues. The role of these two lysine residues in the enzyme mechanism is discussed.
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Conference Article|
August 01 2002
5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism
P. M. Shoolingin-Jordan;
P. M. Shoolingin-Jordan
1
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
1To whom correspondence should be addressed (e-mail pmsj@soton.ac.uk)
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P. Spencer;
P. Spencer
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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M. Sarwar;
M. Sarwar
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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P. E. Erskine;
P. E. Erskine
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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K.-M. Cheung;
K.-M. Cheung
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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J. B. Cooper;
J. B. Cooper
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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E. B. Norton
E. B. Norton
1School of Biological Sciences, Southampton University, Bassett Crescent East, Southampton SO16 7PX, U.K.
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Publisher: Portland Press Ltd
Received:
April 10 2002
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2002 Biochemical Society
2002
Biochem Soc Trans (2002) 30 (4): 584–590.
Article history
Received:
April 10 2002
Citation
P. M. Shoolingin-Jordan, P. Spencer, M. Sarwar, P. E. Erskine, K.-M. Cheung, J. B. Cooper, E. B. Norton; 5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism. Biochem Soc Trans 1 August 2002; 30 (4): 584–590. doi: https://doi.org/10.1042/bst0300584
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