title: The iron-sulfur cluster in the L-serine dehydratase TdcG from Escherichia coli is required for enzyme activity.
abstract: The anaerobically inducible L-serine dehydratase, TdcG, from Escherichia coli was characterized. Based on UV-visible spectroscopy, iron and labile sulfide analyses, the homodimeric enzyme is proposed to have two oxygen-labile [4Fe-4S]2+ clusters. Anaerobically isolated dimeric TdcG had a kcat of 544 s(-1) and an apparent KM for L-serine of 4.8 mM. L-threonine did not act as a substrate for the enzyme. Exposure of the active enzyme to air resulted in disappearance of the broad absorption band at 400-420 nm, indicating a loss of the [4Fe-4S]2+ cluster. A concomitant loss of dehydratase activity was demonstrated, indicating that integrity of the [4Fe-4S]2+ cluster is essential for enzyme activity.
authors.affiliation: Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, UK.
authors.forename: Julia D
authors.initials: JD
authors.lastname: Burman
authors.forename: Roger L
authors.initials: RL
authors.lastname: Harris
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Hauton
authors.forename: David M
authors.initials: DM
authors.lastname: Lawson
authors.forename: R Gary
authors.initials: RG
authors.lastname: Sawers
mesh_terms: D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D007700:Kinetics; D012695:L-Serine Dehydratase / Q000378:metabolism*; D013053:Spectrophotometry; D013440:Sulfides / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D013440:Sulfides; D012695:L-Serine Dehydratase