Transcriptional regulation of nitrogen fixation by molybdenum in Azotobacter vinelandii

Multiple genomic regions homologous to nifH were found in the diazotroph Azotobacter vinelandii. The nifHDK gene cluster, located on a 12.8-kilobase (kb) XhoI fragment and two additional XhoI fragments (7.4 and 8.4 kb) hybridized to a nifH-specific DNA template but the 7.4- and 8.4-kb fragments did not hybridize to nifD- or nifK-specific DNA probes. In vivo transcription of the nifHDK gene cluster was ammonia-repressible and required the presence of at least 50 nM molybdenum in the derepression medium. Three mRNA species were transcribed from the nifHDK gene cluster, a 4.2-kb transcript homologous to nifH-, nifD-, and nifK-specific DNA templates, a 2.6-kb transcript homologous to nifH- and nifD-specific DNA templates, and a 1.2-kb transcript homologous only to the nifH-specific DNA template. In strain CA11, a nifHDK deletion mutant, the nifHDK-specific transcripts were not produced and the strain was unable to grow in N-free medium in the presence of Na2MoO4 at concentrations of 50 nM or higher. However, at concentrations of 25 nM Mo or less, growth occurred in N-free medium. Under these conditions two nifH-homologous (but not nifD- or nifK-homologous) transcripts were observed (1.2 and 1.8 kb). Presumably these were transcribed from the additional nifH-homologous sequences present in the genome. These results are consistent with the existence of two N2 fixation systems in A. vinelandii which are regulated by molybdenum at the level of transcription.

[1]  D. Dean,et al.  Nitrogen Fixation by Azotobacter vinelandii Strains Having Deletions in Structural Genes for Nitrogenase , 1986, Science.

[2]  K. Bott,et al.  Molecular cloning of nif DNA from Azotobacter vinelandii , 1985, Journal of bacteriology.

[3]  C. Quinto,et al.  Nitrogenase reductase: A functional multigene family in Rhizobium phaseoli. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[4]  W. Newton,et al.  Complete nucleotide sequence of the Azotobacter vinelandii nitrogenase structural gene cluster. , 1985, Gene.

[5]  W. Brill,et al.  Role of the nifQ gene product in the incorporation of molybdenum into nitrogenase in Klebsiella pneumoniae , 1984, Journal of bacteriology.

[6]  R. Premakumar,et al.  Evidence for Two Dinitrogenase Reductases under Regulatory Control by Molybdenum in Azotobacter Vinelandii , 1984 .

[7]  R. Haselkorn,et al.  Activation of extra copies of genes coding for nitrogenase in Rhodopseudomonas capsulata , 1984, Nature.

[8]  B. Burgess.  Structure and Reactivity of Nitrogenase — An Overview , 1984 .

[9]  W. Brill,et al.  Molybdenum in nitrogenase. , 1984, Annual review of biochemistry.

[10]  J. Postgate,et al.  Progress in comparative genetics of nitrogen fixation. , 1983, Canadian journal of microbiology.

[11]  R. Rippka,et al.  The structural nif genes of the cyanobacteria Gloeothece sp. and Calothrix sp. share homology with those of Anabaena sp., but the Gloeothece genes have a different arrangement , 1983, Journal of bacteriology.

[12]  R. Haselkorn,et al.  Isolation and physical mapping of nitrogen fixation genes from the cyanobacterium Anabaena 7120. , 1982, The Journal of biological chemistry.

[13]  W. Page,et al.  Molybdenum enhancement of nitrogen fixation in a Mo-starved Azotobacter vinelandii Nif− mutant , 1982 .

[14]  A. van Kammen,et al.  On the operon structure of the nitrogenase genes of Rhizobium leguminosarum and Azotobacter vinelandii. , 1982, Nucleic acids research.

[15]  D. Kahn,et al.  Nitrogen Fixation in Klebsiella pneumoniae: Nitrogenase Levels and the Effect of Added Molybdate on Nitrogenase Derepressed under Molybdenum Deprivation , 1982 .

[16]  M. Norgard.  Rapid and simple removal of contaminating RNA from plasmid DNA without the use of RNase. , 1981, Analytical biochemistry.

[17]  P. Chambon,et al.  A reliable method for the recovery of DNA fragments from agarose and acrylamide gels. , 1981, Analytical biochemistry.

[18]  W. Brill,et al.  Genetics and regulation of nitrogen fixation. , 1981, Annual review of microbiology.

[19]  P. Bishop,et al.  Evidence for an alternative nitrogen fixation system in Azotobacter vinelandii. , 1980, Proceedings of the National Academy of Sciences of the United States of America.

[20]  J. Benemann,et al.  Effect of molybdenum starvation and tungsten on the synthesis and activity of nitrogenase in Anabaena cylindrica , 1980 .

[21]  D. Kahn,et al.  Analysis of regulation of Klebsiella pneumoniae nitrogen fixation (nif) gene cluster with gene fusions , 1980, Nature.

[22]  G. Ruvkun,et al.  Interspecies homology of nitrogenase genes. , 1980, Proceedings of the National Academy of Sciences of the United States of America.

[23]  R. Haselkorn,et al.  Molybdenum independence of nitrogenase component synthesis in the non-heterocystous cyanobacterium Plectonema , 1978, Journal of bacteriology.

[24]  G. Carmichael,et al.  Analysis of single- and double-stranded nucleic acids on polyacrylamide and agarose gels by using glyoxal and acridine orange. , 1977, Proceedings of the National Academy of Sciences of the United States of America.

[25]  J. Postgate,et al.  Expression of Klebsiella pneumoniae nitrogen fixation genes in nitrate reductase mutants of Escherichia coli. , 1977, Journal of general microbiology.

[26]  J. Cárdenas,et al.  Role of molybdenum in dinitrogen fixation by Clostridium pasteurianum , 1975, Journal of bacteriology.

[27]  W. Brill,et al.  Nitrogenase V. The effect of Mo, W and V on the synthesis of nitrogenase components in Azotobacter vinelandii. , 1974, Biochimica et biophysica acta.

[28]  P. W. Wilson,et al.  Formation of the nitrogen-fixing enzyme system in Azotobacter vinelandii. , 1968, Canadian journal of microbiology.

[29]  P. W. Wilson,et al.  A Non-Gummy Chromogenic Strain of Azotobacter vinelandii , 1959, Nature.