Thermal inactivation of reduced ferredoxin (flavodoxin):NADP + oxidoreductase from Escherichia coli

• Published in: FEBS letters Vol. 529; no. 2; pp. 237 - 242
• Main Authors: Jarrett, Joseph T, Wan, Jason T
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 09.10.2002
• Subjects: AdoMet, S-adenosyl-L-methionine; Bis-Tris Propane, 1,3-bis[tris(hydroxymethyl)methylamino]propane; DCIP, 2,6-dichloroindophenol; DTT, dithiothreitol; Enzyme Stability; Escherichia coli - enzymology; Fd, ferredoxin; Ferredoxin-NADP Reductase - antagonists & inhibitors; Ferredoxin-NADP Reductase - metabolism; Ferredoxin:NADP reductase; Flavin-adenine dinucleotide; Flavoprotein; Fld, flavodoxin; FNR, ferredoxin (flavodoxin):NADP+ oxidoreductase; Kinetics; Oxidation-Reduction; Oxidoreductase; Fld, flavodoxin; Bis-Tris Propane, 1,3-bis[tris(hydroxymethyl)methylamino]propane; DCIP, 2,6-dichloroindophenol; Oxidoreductase; Enzyme stability; FNR, ferredoxin (flavodoxin):NADP + oxidoreductase; Flavoprotein; AdoMet, S-adenosyl- L-methionine; Ferredoxin:NADP reductase; Fd, ferredoxin; Flavin-adenine dinucleotide; DTT, dithiothreitol
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(02)03349-5

Ferredoxin (flavodoxin):NADP + oxidoreductase (FNR) is an essential enzyme that supplies electrons from NADPH to support flavodoxin-dependent enzyme radical generation and enzyme activation. FNR is a monomeric enzyme that contains a non-covalently bound FAD cofactor. We report that reduced FNR from Escherichia coli is subject to inactivation due to unfolding of the protein and dissociation of the FADH 2 cofactor at 37°C. The inactivation rate is temperature-dependent in a manner that parallels the thermal unfolding of the protein and is slowed by binding of ferredoxin or flavodoxin. Understanding factors that minimize inactivation is critical for utilizing FNR as an accessory protein for S-adenosyl- L-methionine-dependent radical enzymes and manipulating FNR as an electron source for biotechnology applications.