The Involvement of the nif-Associated Ferredoxin-Like Genes fdxA and fdxN of Herbaspirillum seropedicae in Nitrogen Fixation

The pathway of electron transport to nitrogenase in the endophytic β-Proteobacterium Herbaspirillum seropedicae has not been characterized. We have generated mutants in two nif-associated genes encoding putative ferredoxins, fdxA and fdxN. The fdxA gene is part of the operon nifHDKENXorf1orf2fdxAnif...

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Veröffentlicht in:The journal of microbiology Jg. 48; H. 1; S. 77 - 83
Hauptverfasser: Souza, Andre L.F., Universidade Federal do Parana, CP, Brazil, Invitti, Adriana L., Universidade Federal do Parana, CP, Brazil, Rego, Fabiane G.M., Universidade Federal do Parana, CP, Brazil, Monteiro, Rose A., Universidade Federal do Parana, CP, Brazil, Klassen, Giseli, Universidade Federal do Parana, CP, Brazil, Souza, Emanuel M., Universidade Federal do Parana, CP, Brazil, Chubatsu, Leda S., Universidade Federal do Parana, CP, Brazil, Pedrosa, Fabio O., Universidade Federal do Parana, CP, Brazil, Rigo, Liu U., Universidade Federal do Parana, CP, Brazil
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Heidelberg The Microbiological Society of Korea 01.02.2010
Springer Nature B.V
한국미생물학회
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ISSN:1225-8873, 1976-3794, 1976-3794
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Zusammenfassung:The pathway of electron transport to nitrogenase in the endophytic β-Proteobacterium Herbaspirillum seropedicae has not been characterized. We have generated mutants in two nif-associated genes encoding putative ferredoxins, fdxA and fdxN. The fdxA gene is part of the operon nifHDKENXorf1orf2fdxAnifQmodABC and is transcribed from the nifH promoter, as revealed by lacZ gene fusion. The fdxN gene is probably co-transcribed with the nifB gene. Mutational analysis suggests that the FdxA protein is essential for maximum nitrogenase activity, since the nitrogenase activity of the fdxA mutant strain was reduced to about 30% of that of the wild-type strain. In addition, the fdxA mutation had no effect on the nitrogenase switch-off in response to ammonium. Nitrogenase activity of a mutant strain lacking the fdxN gene was completely abolished. This phenotype was reverted by complementation with fdxN expressed under lacZ promoter control. The results suggest that the products of both the fdxA and fdxN genes are probably involved in electron transfer during nitrogen fixation.
Bibliographie:A50
2011003011
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G704-000121.2010.48.1.007
ISSN:1225-8873
1976-3794
1976-3794
DOI:10.1007/s12275-009-0077-y