The iron-sulfur cluster in the L-serine dehydratase TdcG from Escherichia coli is required for enzyme activity.
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.
Burman
Julia D
JD
Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, UK.
Harris
Roger L
RL
Hauton
Katherine A
KA
Lawson
David M
DM
Sawers
R Gary
RG
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
D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D013440:Sulfides; D012695:L-Serine Dehydratase