Journal Article

Molybdate-dependent expression of dimethylsulfoxide reductase in Rhodobacter capsulatus

Peter S. Solomon, Anthony L. Shaw, Michael D. Young, Silke Leimkuhler, Graeme R. Hanson, Werner Klipp and Alastair G. McEwan

in FEMS Microbiology Letters

Volume 190, issue 2, pages 203-208
Published in print September 2000 |
Published online January 2006 | e-ISSN: 1574-6968 | DOI:

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Expression of the dimethylsulfoxide respiratory (dor) operon of Rhodobacter is regulated by oxygen, light intensity and availability of substrate. Since dimethylsulfoxide reductase contains a pterin molybdenum cofactor, the role of molybdate in the regulation of dor operon expression was investigated. In this report we show that the molybdate-responsive transcriptional regulator, MopB, and molybdate are essential for maximal dimethylsulfoxide reductase activity and expression of a dorA::lacZ transcriptional fusion in Rhodobacter capsulatus. In contrast, mop genes are not required for the expression of the periplasmic nitrate reductase or xanthine dehydrogenase in R. capsulatus under conditions of molybdenum sufficiency. This is the first report demonstrating a clear functional difference between the ModE homologues MopB and MopA in this bacterium. The results suggest that MopA is primarily involved in the regulation of nitrogen fixation gene expression in response to molybdate while MopB has a role in nitrogen fixation and dimethylsulfoxide respiration.

Keywords: Dimethylsulfoxide reductase; Molybdate-dependent gene expression; mop genes; Rhodobacter

Journal Article.  2991 words.  Illustrated.

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