Characterization of the molybdate transport system ModABC of Staphylococcus carnosus.
Transposon mutagenesis of Staphylococcus carnosus led to the identification of three genes, modABC, which encode an ABC transporter that is involved in molybdate transport. It was shown by [14C]palmitate labeling that ModA represents a lipoprotein that in gram-positive bacteria is the counterpart of the periplasmic binding proteins of gram-negative organisms. The sequence characteristics identify ModB as the integral-membrane, channel-forming protein and ModC as the ATP-binding energizer for the transport system. Mutants defective in modABC had only 0.4% of the wild-type nitrate reductase activity. Molybdate at a non-physiologically high concentration (100 microM) fully restored nitrate reductase activity, suggesting that at least one other system is able to transport molybdate, but with lower affinity. The expression of modA (and most likely of modBC) was independent of oxygen and nitrate. To date, there are no indications for molybdate-specific regulation of modABC expression since in a modB mutant, modA expression was unchanged in comparison to the wild-type.
Mikrobielle Genetik, Universität Tübingen, Waldhäuser Strasse 70/8, D-72076 Tübingen, Germany.
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Neubauer
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Pantel
P E
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Lindgren
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Götz
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003067:Coenzymes; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D008667:Metalloproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism*; D000090006:Molybdenum Cofactors; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000096:biosynthesis; D009566:Nitrates / Q000378:metabolism*; D010084:Oxidation-Reduction; D033902:Periplasmic Binding Proteins; D011621:Pteridines / Q000378:metabolism; D013210:Staphylococcus / Q000502:physiology*
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D003067:Coenzymes; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D050901:Nitrate Reductase; D009565:Nitrate Reductases; D009566:Nitrates; D033902:Periplasmic Binding Proteins; D011621:Pteridines; C098002:ModA protein, E coli; C044659:molybdate; C022261:molybdopterin