Genetic determinants of a nickel-specific transport system are part of the plasmid-encoded hydrogenase gene cluster in Alcaligenes eutrophus. |
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| Authors: | G Eberz T Eitinger B Friedrich |
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| Affiliation: | Institut für Pflanzenphysiologie, Zellbiologie und Mikrobiologie, Freien Universit?t Berlin, Federal Republic of Germany. |
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| Abstract: | Nickel-deficient (Nic-) mutants of Alcaligenes eutrophus requiring high levels of nickel ions for autotrophic growth with hydrogen were characterized. The Nic- mutants carried defined deletions in the hydrogenase gene cluster of the indigenous pHG megaplasmid. Nickel deficiency correlated with a low level of the nickel-containing hydrogenase activity, a slow rate of nickel transport, and reduced activity of urease. The Nic+ phenotype was restored by a cloned DNA sequence (hoxN) of a megaplasmid pHG1 DNA library of A. eutrophus H16. hoxN is part of the hydrogenase gene cluster. The nickel requirement of Nic- mutants was enhanced by increasing the concentration of magnesium. This suggests that the Nic- mutants are impaired in the nickel-specific transport system and thus depend on the second transport activity which normally mediates the uptake of magnesium. |
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