Enzymatic and physiological properties of the tungsten-substituted molybdenum TMAO reductase from Escherichia coli.
The trimethylamine N-oxide (TMAO) reductase of Escherichia coli is a molybdoenzyme that catalyses the reduction of the TMAO to trimethylamine (TMA) with a redox potential of +130 mV. We have successfully substituted the molybdenum with tungsten and obtained an active tungsto-TMAO reductase. Kinetic studies revealed that the catalytic efficiency of the tungsto-substituted TMAO reductase (W-TorA) was increased significantly (twofold), although a decrease of about 50% in its kcat was found compared with the molybdo-TMAO reductase (Mo-TorA). W-TorA is more sensitive to high pH, is less sensitive to high NaCl concentration and is more heat resistant than Mo-TorA. Most importantly, the W-TorA becomes capable of reducing sulphoxides and supports the anaerobic growth of a bacterial host on these substrates. The evolutionary implication and mechanistic significance of the tungsten substitution are discussed.
Buc
J
J
Laboratoire de Chimie Bactérienne, CNRS, Marseille, France.
Santini
C L
CL
Giordani
R
R
Czjzek
M
M
Wu
L F
LF
Giordano
G
G
D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007506:Iron-Sulfur Proteins; D007700:Kinetics; D008982:Molybdenum / Q000378:metabolism; D016296:Mutagenesis; D010088:Oxidoreductases / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology*; D013696:Temperature; D013997:Time Factors; D014414:Tungsten / Q000378:metabolism
D007506:Iron-Sulfur Proteins; D008982:Molybdenum; D010088:Oxidoreductases; D010089:Oxidoreductases, N-Demethylating; C023186:trimethylamine dehydrogenase; C045664:dimethyl sulfoxide reductase; D014414:Tungsten