The ferredoxin-encoding fdxN gene of the filamentous cyanobacterium Anabaena variabilis ATCC 29413 is not essential for nitrogen fixation

Bernd Masepohl; Kirsten Görlitz; Ursula Monnerjahn; Britta Moslerand; Herbert Böhme

doi:10.1046/j.1469-8137.1997.00771.x

The ferredoxin-encoding fdxN gene of the filamentous cyanobacterium Anabaena variabilis ATCC 29413 is not essential for nitrogen fixation

New Phytol. 1997 Jul;136(3):419-423. doi: 10.1046/j.1469-8137.1997.00771.x.

Authors

Bernd Masepohl¹, Kirsten Görlitz¹, Ursula Monnerjahn¹, Britta Moslerand¹, Herbert Böhme¹

Affiliation

¹ Botanisches Institut der Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany.

PMID: 33863005
DOI: 10.1046/j.1469-8137.1997.00771.x

Abstract

In contrast to that of Anabaena sp. PCC7120, the fdxN gene in Anabaena variabilis ATCC 29413 is not interrupted by a 55-kb DNA element, making this strain more suitable for genetic analysis of fdxN independent of the developmentally regulated excision during heterocyst formation. As a basis for mutational analysis, the fdxN gene of A. variabilis was cloned and sequenced. The deduced FdxN protein sequence was highly homologous to the Anabaena 7120 fdxN gene product including eight cysteine residues that are known to be conserved among ferredoxins containing two [4Fe-4S] clusters. The fdxN gene of A. variabilis was disrupted by insertion of an interposon within the fdxN coding region resulting in mutant strain KG29. Diazotrophic growth and in vivo nitrogenase activity of KG29 were similar to those of the wild-type, indicating that FdxN was not essential for N₂ fixation in A. variabilis.

Keywords: 55-kb fdxN DNA element; Anabaena sp.; bacterial-type ferredoxin; heterocysts; nifB-fdxN-nifS-nifU operon.