Nucleotide sequence of the gene encoding the nitrogenase iron protein (nifH) of Azospirillum brasilense and identification of a region controlling nifH transcription

The DNA sequence was determined for the Azospirillum brasilense nifH gene and part of the nifD gene. The nifH gene is 885 bp long and encodes 293 amino acid residues. The region upstream of the nifH open reading frame contains a putative promoter whose sequence shows perfect homology with promoters...

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Bibliographic Details
Published inMolecular & general genetics Vol. 220; no. 1; pp. 81 - 87
Main Authors Fani, R, Allotta, G, Bazzicalupo, M, Ricci, F, Schipani, C, Polsinelli, M
Format Journal Article
LanguageEnglish
Published Germany 01.12.1989
Subjects
Amino Acid Sequence
Azospirillum brasilense
Azospirillum brasilense - genetics
Azospirillum brasilense - growth & development
Base Sequence
Codon
DNA
DNA, Fungal - genetics
Genes, Bacterial
genetic code
genetic control
Molecular Sequence Data
Nitrogen Fixation - genetics
nitrogen-fixing bacteria
nitrogenase
Nitrogenase - genetics
nucleotide sequences
Oxidoreductases
Phylogeny
Poaceae
Restriction Mapping
Sequence Homology, Nucleic Acid
Transcription, Genetic
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Summary:The DNA sequence was determined for the Azospirillum brasilense nifH gene and part of the nifD gene. The nifH gene is 885 bp long and encodes 293 amino acid residues. The region upstream of the nifH open reading frame contains a putative promoter whose sequence shows perfect homology with promoters of other diazotrophic bacteria and two putative upstream activator sequences. Experiments with the promoter-probe vector pAF300 showed that this region promotes transcription in response to the nitrogen and oxygen availability of the cell. The amino acid sequence was deduced from the DNA nucleotide sequence of nifH; the polypeptide contains the four cysteine residues highly conserved among other nifH products and an arginine residue at position 101 which could be the site of the modification occurring during the "switch-off" of nitrogenase. The codon usage appears to be very biased reflecting the high G + C content of the Azospirillum nifH gene. In a comparison of the amino acid sequence with the other 18 known nifH gene products, the A. brasilense nifH product showed the highest level of homology with fast-growing Rhizobia suggesting interesting evolutionary implications.
ISSN:0026-8925
1432-1874
DOI:10.1007/BF00260860