1QML image
Entry Detail
PDB ID:
1QML
Keywords:
Title:
Hg complex of yeast 5-aminolaevulinic acid dehydratase
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
1999-10-02
Release Date:
2000-10-06
Method Details:
Experimental Method:
Resolution:
3.00 Å
R-Value Free:
0.33
R-Value Work:
0.24
Space Group:
I 4 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:5-AMINOLAEVULINIC ACID DEHYDRATASE
Chain IDs:A
Chain Length:342
Number of Molecules:1
Biological Source:SACCHAROMYCES CEREVISIAE
Ligand Molecules
Primary Citation
MAD Analyses of Yeast 5-Aminolaevulinic Acid Dehydratase. Their Use in Structure Determination and in Defining the Metal Binding Sites
Acta Crystallogr.,Sect.D 56 421 ? (2000)
PMID: 10739915 DOI: 10.1107/S0907444900000597

Abstact

MAD experiments attempting to solve the structure of 5--aminolaevulinic acid dehydratase using Zn and Pb edges are described. The data obtained proved insufficient for a complete structure solution but were invaluable in subsequent identification of metal-binding sites using anomalous difference Fourier analyses once the structure of the enzyme had been solved. These sites include the highly inhibitory substitution of an enzymic cofactor Zn(2+) ion by Pb(2+) ions, which represents a major contribution towards understanding the molecular basis of lead poisoning. The MAD data collected at the Pb edge were also used with isomorphous replacement data from the same Pb co-crystal and a Hg co-crystal to provide the first delineation of the enzyme's quaternary structure. In this MADIR analysis, the Hg co-crystal data were treated as native data. Anomalous difference Fouriers were again used, revealing that Hg(2+) had substituted for the same Zn(2+) cofactor ion as had Pb(2+), a finding of fundamental importance for the understanding of mercury poisoning. In addition, Pt(2+) ions were found to bind at the same place in the structure. The refined structures of the Pb- and the Hg-complexed enzymes are presented at 2.5 and 3.0 A resolution, respectively.

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