The nucleotide sequence of a 1 kb fragment upstream of Azorhizobium caulinodans fixL was established. An open reading frame of 744 bp was identified as a fixK homologue. A kanamycin cartridge was inserted into the cloned fixK-like gene and recombined into the host genome. The resulting mutant was Nif-Fix-, suggesting that FixK was required for nitrogen fixation both in symbiotic conditions and in the free-living state. Using a pfixK-lacZ fusion, the FixLJ products were shown to control the expression of fixK. Using a pnifA-lacZ fusion, the FixK product was shown to regulate positively the transcription of nifA in bacteria grown in the free-living state. In addition, a double ntrC-fixL mutant was constructed and was shown to be completely devoid of nitrogenase activity. A model of regulation, based on these data, is presented and might explain the unusual ability of A. caulinodans to fix nitrogen both under symbiotic conditions and in the free-living state.
| Predicate | Object |
|---|---|
| rdf:type | |
| rdfs:comment |
The nucleotide sequence of a 1 kb fragment upstream of Azorhizobium caulinodans fixL was established. An open reading frame of 744 bp was identified as a fixK homologue. A kanamycin cartridge was inserted into the cloned fixK-like gene and recombined into the host genome. The resulting mutant was Nif-Fix-, suggesting that FixK was required for nitrogen fixation both in symbiotic conditions and in the free-living state. Using a pfixK-lacZ fusion, the FixLJ products were shown to control the expression of fixK. Using a pnifA-lacZ fusion, the FixK product was shown to regulate positively the transcription of nifA in bacteria grown in the free-living state. In addition, a double ntrC-fixL mutant was constructed and was shown to be completely devoid of nitrogenase activity. A model of regulation, based on these data, is presented and might explain the unusual ability of A. caulinodans to fix nitrogen both under symbiotic conditions and in the free-living state.
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| skos:exactMatch | |
| uniprot:name |
Mol. Microbiol.
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| uniprot:author |
Arigoni F.,
Desnoues N.,
Elmerich C.,
Kaminski P.A.,
Mandon K.
|
| uniprot:date |
1991
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| uniprot:pages |
1983-1991
|
| uniprot:title |
Regulation of nitrogen fixation in Azorhizobium caulinodans: identification of a fixK-like gene, a positive regulator of nifA.
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| uniprot:volume |
5
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| dc-term:identifier |
doi:10.1111/j.1365-2958.1991.tb00820.x
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