Progress in comparative genetics of nitrogen fixation

Robson, Richard M.; Kennedy, Christina; Postgate, J. R.

doi:10.1139/m83-152

Cited by 21 publications

(2 citation statements)

References 128 publications

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“…We infer that the nitrogenase structural genes of this strain are located on the chromosome. This has generally been found to be the case amongst free-living diazotrophic bacteria (Robson et al, 1983), though exceptions are known (Derylo et al, 1981;Singh et al, 1983).…”

Section: Discussionmentioning

confidence: 96%

Physiological and Genetic Characterization of a Diazotrophic Pseudomonad

Chan¹,

Wheatcroft²,

Watson³

1986

Microbiology

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A soil isolate, 4B, which had been previously assigned to the genus Pseudomonas and shown to be capable of reducing C2H2 with simple phenolic compounds as sole carbon source, was further characterized in comparison with two other diazotrophs which were identified as pseudomonads. The DNA base composition of 4B was 60.2 mol% G + C. Plasmid DNA was not detected in Y.-K. C H A N A N D OTHERS METHODS Bacterial strains, plasmids and DNA.Strain 4B, which has been tentatively assigned to the genus Pseudomonas, was originally isolated from a forest soil (Chan, 1986) and was recently deposited in the American Type Culture Collection (ATCC 43038). P. delafieldii (ATCC 17505) and P . putida (ATCC 33015) were obtained from the ATCC. Pseudomonas strain H8 (ATCC 35402) was a gift from W. ). Pseudomonas strain DC, originally isolated from the roots of the grass Deschampsia caespitosa (Haahtela et al., 1983), was kindly sent to us by K. Haahtela (University of Helsinki, Finland). Klebsiella pneumoniae M5A1 was obtained from V. N. Iyer, (Carleton University, Ottawa, Canada); Escherichia coli 553 (proA metF A) carrying plasmid RP4 (AprKmr NmrTcr) was from the Plasmid Referencecenter, Stanford University, USA ; E. coli B was from the Department of Microbiology, University of Manitoba, Canada; and E. coli HBlOl(pSA30) was from D. R. Helinski, (University of California, USA).Reference DNAs of Clostridiumperfringens, E. coli B and Micrococcus lysodeikticus were purchased from Sigma.Culture media. The maintenance agar used for the diazotrophic species consisted of 0.1 % (w/v) Difco tryptic soy broth solidified with 1.6% (w/v) Difco Bacto-agar; P. delafieldii was maintained on nutrient agar. Tests for autotrophic growth with Hz, O2 and C 0 2 were done in the defined medium described by De Bont & Leijten (1976).

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Section: Discussionmentioning

confidence: 96%

Physiological and Genetic Characterization of a Diazotrophic Pseudomonad

Chan¹,

Wheatcroft²,

Watson³

1986

Microbiology

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“…Nitrogen fixation, an exclusively prokaryotic process whereby molecular dinitrogen is transformed into ammonia, is not limited to the primary domain Bacteria but is also observed in several methanogenic members of the domain Archaea (5,6,31). In Bacteria, the organization and regulated expression of nitrogen fixation (nif) genes have been described for a variety of species (15,22,35,36). The genes nifH, nifD, and nifK are typically found together in a single operon and are physically adjacent to other nif genes as part of a larger nif regulon.…”

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confidence: 99%

The nif Gene Operon of the Methanogenic Archaeon Methanococcus maripaludis

1998

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Nitrogen fixation occurs in two domains, Archaea andBacteria. We have characterized a nif(nitrogen fixation) gene cluster in the methanogenic archaeonMethanococcus maripaludis. Sequence analysis revealed eight genes, six with sequence similarity to known nif genes and two with sequence similarity to glnB. The gene order,nifH, ORF105 (similar to glnB),ORF121 (similar to glnB), nifD,nifK, nifE, nifN, andnifX, was the same as that found in part in other diazotrophic methanogens and except for the presence of theglnB-like genes, also resembled the order found in many members of the Bacteria. Using transposon insertion mutagenesis, we determined that an 8-kb region required for nitrogen fixation corresponded to the nif gene cluster. Northern analysis revealed the presence of either a single 7.6-kbnif mRNA transcript or 10 smaller mRNA species containing portions of the large transcript. Polar effects of transposon insertions demonstrated that all of these mRNAs arose from a single promoter region, where transcription initiated 80 bp 5′ tonifH. Distinctive features of the nif gene cluster include the presence of the six primary nif genes in a single operon, the placement of the two glnB-like genes within the cluster, the apparent physical separation of the cluster from any other nif genes that might be in the genome, the fragmentation pattern of the mRNA, and the regulation of expression by a repression mechanism described previously. Our study and others with methanogenic archaea reporting multiple mRNAs arising from gene clusters with only a single putative promoter sequence suggest that mRNA processing following transcription may be a common occurrence in methanogens.

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