Expression of the nap operon, encoding the periplasmic nitrate reductase in Paracoccus pantotrophus, is maximal when cells are grown aerobically, but not anaerobically, with butyrate. Two promoters, termed P1 and P2, control operon expression and the operon-proximal P2 promoter is primarily responsible for increased nap expression in the presence of butyrate. A near-perfect palindromic sequence is centred at +7, relative to the P2 transcription start site.
View Article and Find Full Text PDFAlkene monooxygenase (AMO) from Rhodococcus rhodochrous (formerly Nocardia corallina) B-276 belongs to a family of multicomponent nonheme binuclear iron-centre oxygenases that includes the soluble methane monooxygenases (sMMOs) found in some methane-oxidizing bacteria. The enzymes catalyse the insertion of oxygen into organic substrates (mostly hydrocarbons) at the expense of O2 and NAD(P)H. AMO is remarkable in its ability to oxidize low molecular-mass alkenes to their corresponding epoxides with high enantiomeric excess.
View Article and Find Full Text PDFAlkene monooxygenase (AMO) from Rhodococcus rhodochrous (formerly Nocardia corallina) B-276 is a three-component enzyme system encoded by the four-gene operon amoABCD. AMO catalyses the stereoselective epoxygenation of aliphatic alkenes, yielding primarily R enantiomers. The presumed site of alkene oxygenation is a dinuclear iron centre similar to that in the soluble methane monooxygenases of methanotrophic bacteria, to which AMO exhibits a significant degree of amino acid sequence identity.
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