One protein, two enzymes.
Two enzymes, designated, E-2 and E-2', catalyze different oxidation reactions of an aci-reductone intermediate in the methionine salvage pathway. E-2 and E-2', overproduced in Escherichia coli from the same gene, have the same protein component. E-2 and E-2' are separable on an anion exchange column or a hydrophobic column. Their distinct catalytic and chromatographic properties result from binding different metals. The apo-enzyme, obtained after metal is removed from either enzyme, is catalytically inactive. Addition of Ni2+ or Co2+ to the apo-protein yields E-2 activity. E-2' activity is obtained when Fe2+ is added. Production in intact E. coli of E-2 and E-2' depends on the availability of the corresponding metals. These observations suggest that the metal component dictates reaction specificity.
Dai
Y
Y
Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453-2728, USA.
Wensink
P C
PC
Abeles
R H
RH
D020134:Catalytic Domain; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003035:Cobalt / Q000378:metabolism; D049308:Dioxygenases; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D005296:Ferrous Compounds / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics; D008715:Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D005296:Ferrous Compounds; D011994:Recombinant Proteins; D003035:Cobalt; C014632:2-keto-4-methylthiobutyric acid; D009532:Nickel; D008715:Methionine; D010105:Oxygenases; D049308:Dioxygenases; C083734:aci-reductone oxidase (CO-forming)