The molybdenum cofactor biosynthesis protein MobA from Rhodobacter capsulatus is required for the activity of molybdenum enzymes containing MGD, but not for xanthine dehydrogenase harboring the MPT cofactor

Authors

  • Silke Leimkühler,

    1. Ruhr-Universität Bochum, Fakultät für Biologie, Lehrstuhl für Biologie der Mikroorganismen, D-44780 Bochum, Germany
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    • 1Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.

  • Werner Klipp

    Corresponding author
    1. Ruhr-Universität Bochum, Fakultät für Biologie, Lehrstuhl für Biologie der Mikroorganismen, D-44780 Bochum, Germany
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*Corresponding author. Tel.: +49 (234) 700-3100; Fax: +49 (234) 7094-620; E-mail: werner.klipp@ruhr-uni-bochum.de

Abstract

The requirement of MobA for molybdoenzymes with different molybdenum cofactors was analyzed in Rhodobacter capsulatus. MobA is essential for DMSO reductase and nitrate reductase activity, both enzymes containing the molybdopterin guanine dinucleotide cofactor (MGD), but not for active xanthine dehydrogenase, harboring the molybdopterin cofactor. In contrast to the mob locus of Escherichia coli and R. sphaeroides, the mobB gene is not located downstream of mobA in R. capsulatus. The mobA gene is expressed constitutively at low levels and no increase in mobA expression could be observed even under conditions of high MGD demand.

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