Disease relevance of fdxH

• Southern hybridization detected only one copy of the fdxH gene in the Anabaena 7120 genome [1].
• To identify amino acids that are important for interaction with nitrogenase, we generated site-directed mutations in the fdxH gene and assayed the in vitro activity of the resulting recombinant proteins isolated from Escherichia coli [2].
• A genomic DNA region with four consecutive open reading frames, including an fdxH-type gene, has been sequenced and initially characterized for the nonheterocystous nitrogen-fixing cyanobacterium Plectonema boryanum PCC 73110 [3].
• An fdxB-type gene encoding a 2[4Fe-4S] ferredoxin not previously identified in cyanobacteria is located immediately downstream of fdxH in P. boryanum [3].
• Genes homologous to ORF3 from the fdxH gene regions of A. variabilis and Plectonema boryanum, the mop genes of Clostridium pasteurianum encoding molybdo-pterin binding proteins, and ORF3 from the A. variabilis hydrogenase gene cluster were identified within the sequenced region [4].

High impact information on fdxH

• Analysis of the hyperfine-shifted nitrogen-15 resonances of the oxidized form of Anabaena 7120 heterocyst ferredoxin [5].
• Mutations of surface residues in Anabaena vegetative and heterocyst ferredoxin that affect thermodynamic stability as determined by guanidine hydrochloride denaturation [6].
• Under iron stress but in the presence of combined nitrogen, fdxH and nifH genes were transcriptionally active; although excision of the 11-kb element seemed to be completed, nitrogenase activity and the fdxH gene product were not detectable [7].
• Characterization of the genome region encoding an fdxH-type ferredoxin and a new 2[4Fe-4S] ferredoxin from the nonheterocystous, nitrogen-fixing cyanobacterium Plectonema boryanum PCC 73110 [3].
• Two open reading frames that precede fdxH have high similarity to those found at a corresponding location in Anabaena sp. strain PCC 7120 [3].

Chemical compound and disease context of fdxH

• Assuming proteolytic cleavage of the first methionine residue, the molecular weight of Anabaena 7120 heterocyst ferredoxin is 10,806 [1].
• To clarify the role of the heterocyst-specific [2Fe-2S] ferredoxin in cyanobacterial nitrogen fixation, mutational analysis of the Anabaena 7120 fdxH gene region was carried out [4].

Biological context of fdxH

• The sequence of the entire fdxH coding region was determined including 3' and 5' flanking sequences [1].
• Molecular cloning and nucleotide sequence analysis of the gene coding for heterocyst ferredoxin from the cyanobacterium Anabaena sp. strain PCC 7120 [1].
• The structural gene for this heterocyst ferredoxin, fdxH, was isolated from a recombinant lambda library, using an oligonucleotide probe derived from a unique segment of the N-terminal amino acid sequence of the purified protein [1].
• Comparison of LAK4 and BMB92 indicated that one of the genes located downstream of fdxH might also play a (minor) role in nitrogen fixation [4].
• Evidence from directed mutagenesis that positively charged amino acids are necessary for interaction of nitrogenase with the [2Fe-2S] heterocyst ferredoxin (FdxH) from the cyanobacterium Anabaena sp., PCC7120 [2].

Associations of fdxH with chemical compounds

• Exchange of residue F65 for aliphatic substitutions, which was crucial to electron transfer to ferredoxin:NADP-reductase and nitrite reductase, exhibited only small effects on glutamate synthase-dependent activity while heterocyst ferredoxin and flavodoxin were almost inactive as electron donors [8].

Other interactions of fdxH

• The fdxH gene encodes a [2Fe-2S]-type ferredoxin, 98 amino acids in length, with a deduced molecular mass of 10.9 kDa [3].
• Iron concentrations (1 microM Fe) sufficient to induce synthesis of the vegetative cell flavodoxin did not stimulate diazotrophic growth of the fdxH mutant strains, suggesting that FdxH was not replaced by a NifJ-flavodoxin system [4].

References