Expression and flavinylation of Arthrobacter oxydans 6-hydroxy-D-nicotine oxidase in Bacillus subtilis

• 6-Hydroxy-d-nicotine oxidase (6-HDNO) of Arthrobacter oxydans, an enzyme inducible by dl-nicotine, contains FAD covalently bound via an 8α-N(3)His linkage. Expression of the gene encoding 6-HDNO and flavinylation of the protein were studied in Bacillus subtilis. In this heterologous system the following findings were made. 1. An enzymically active covalently flavinylated 6-HDNO of normal size can be expressed in B. subtilis. 2. The natural promoter of the 6-HDNO gene appeared inefficient in B. subtilis. The B. subtilis sdh promoter, when inserted upstream of the A. oxydans promoter, increased 6-HDNO expression >50-fold. 3. Expression of the 6-HDNO gene from plasmids in B. subtilis was, independently of the promoter construct used, stimulated more than fivefold by dl-nicotine in the growth medium. It is concluded that flavinylation of 6-HDNO is possibly autocatalytic and mediated by factors generally found in bacterial cells.

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NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

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