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5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism

5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism
5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism
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.
0300-5127
584-590
Shoolingin-Jordan, P.M.
ac0bf2cc-ee36-4b30-bcef-525cee2559f7
Spencer, P.
cabde954-59c4-48cc-b767-0f66b8bd49ed
Sarwar, M.
5b6c7791-3f9b-43a2-a0a3-38e8289a8fde
Erskine, P.E.
f3ee67b7-07a9-42f2-9495-c742045baff0
Cheung, K.M.
e3159517-c21b-46a8-b78c-9fea919c5d67
Cooper, J.B.
d9f0f6a8-1260-48fc-aa5c-3dbc650e3ec0
Norton, E.B.
18b26151-87ba-48e2-a918-a7aacef9dcbc
Shoolingin-Jordan, P.M.
ac0bf2cc-ee36-4b30-bcef-525cee2559f7
Spencer, P.
cabde954-59c4-48cc-b767-0f66b8bd49ed
Sarwar, M.
5b6c7791-3f9b-43a2-a0a3-38e8289a8fde
Erskine, P.E.
f3ee67b7-07a9-42f2-9495-c742045baff0
Cheung, K.M.
e3159517-c21b-46a8-b78c-9fea919c5d67
Cooper, J.B.
d9f0f6a8-1260-48fc-aa5c-3dbc650e3ec0
Norton, E.B.
18b26151-87ba-48e2-a918-a7aacef9dcbc

Shoolingin-Jordan, P.M., Spencer, P., Sarwar, M., Erskine, P.E., Cheung, K.M., Cooper, J.B. and Norton, E.B. (2002) 5-Aminolaevulinic acid dehydratase: metals, mutants and mechanism. Biochemical Society Transactions, 30 (4), 584-590.

Record type: Article

Abstract

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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More information

Published date: 1 August 2002

Identifiers

Local EPrints ID: 56111
URI: http://eprints.soton.ac.uk/id/eprint/56111
ISSN: 0300-5127
PURE UUID: 9be35a04-6f1c-44d1-a6e9-bb8e26518a1c

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Date deposited: 06 Aug 2008
Last modified: 08 Jan 2022 16:03

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Contributors

Author: P. Spencer
Author: M. Sarwar
Author: P.E. Erskine
Author: K.M. Cheung
Author: J.B. Cooper
Author: E.B. Norton

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