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Gene Review

ntcA  -  nitrogen-responsive regulatory protein

Nostoc sp. PCC 7120

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Disease relevance of ntcA


High impact information on ntcA

  • The induction of the use of these tsps did not take place in ntcA or hetR mutant strains [4].
  • Expression of ntcA in nitrogen-fixing cultures was higher than in cells growing in the presence of ammonium or nitrate, and high expression of ntcA under nitrogen deficiency resulted from an increased use of tsps located at positions -180 and -49 [4].
  • A transcription start point of the Anabaena glnA gene (corresponding to RNAl), that has been shown to be used preferentially after nitrogen step-down, was not used in the ntcA insertional mutant [5].
  • In this work, we describe the isolation of an ntcA insertional mutant of the dinitrogen-fixing, heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 [5].
  • Nitrogenase and enzymes of the nitrate reduction system were not synthesized in the ntcA mutant under derepressing conditions, and glutamine synthetase levels were lower in the mutant than in the wild-type strain [5].

Biological context of ntcA

  • Sequences hybridizing to ntcA have been detected in the genomes of nine other cyanobacteria that were tested, including strains of the genera Anabaena, Calothrix, Fischerella, Nostoc, Pseudoanabaena, Synechococcus, and Synechocystis [3].
  • Complementation of the ntcA mutant with a DNA fragment containing the ntcA gene and 251 bp of upstream sequence on a shuttle vector restored a wild-type phenotype; however, a similar construction containing 87 bp of upstream sequence only partially restored the phenotype [2].
  • As a step towards the goal of understanding the role of VF1 in regulating gene expression, we have cloned the bifA gene by using a genetic selection strategy. bifA encodes a protein, BifA, that has chromatographic and DNA-binding properties indistinguishable from those of VF1 [6].
  • The ntcA product, NtcA, showed binding to the promoter region of its own gene [7].
  • Heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120 depends on both the global nitrogen control transcription factor NtcA and the cell differentiation regulatory protein HetR, with expression of ntcA and hetR being dependent on each other [8].

Associations of ntcA with chemical compounds

  • The ntcA mutant was not able to grow with nitrate or atmospheric dinitrogen as the sole nitrogen source but could be grown on medium containing ammonium [2].

Other interactions of ntcA

  • Northern analysis of RNA samples isolated from ammonium-grown cultures of the ntcA mutant showed reduced amounts of glnA message and the absence of a 1.7-kb transcript [2].
  • The ntcA mutant was unable to form heterocysts and did not rearrange the nifD or fdxN elements after induction on a medium lacking combined nitrogen [2].
  • Overexpression of ntcA in a hetR background promoted expression of devBCA in response to ammonium withdrawal and excision of the 11-kb element even in the presence of combined nitrogen [8].
  • Expression of hetC, tested by RNA- DNA hybridization, was impaired in an ntcA mutant [9].
  • The promoter of the nifHDK operon was active only in heterocysts; the promoter of the nifJ gene was active only in iron-depleted medium; and the promoters of the psbB gene, the ntcA gene, and a newly found transcription factor gene were all active in both cell types [10].

Analytical, diagnostic and therapeutic context of ntcA

  • Great differences in a Northern blot, probed with furA, of RNA from an ntcA mutant relative to wild-type Anabaena sp. were attributable to binding of NtcA, a global regulator of nitrogen metabolism, to the promoter of furA and to the promoter of the furA antisense transcript alr1690-alpha-furA [11].


  1. Regulation of intracellular free calcium concentration during heterocyst differentiation by HetR and NtcA in Anabaena sp. PCC 7120. Shi, Y., Zhao, W., Zhang, W., Ye, Z., Zhao, J. Proc. Natl. Acad. Sci. U.S.A. (2006) [Pubmed]
  2. Anabaena sp. strain PCC 7120 ntcA gene required for growth on nitrate and heterocyst development. Wei, T.F., Ramasubramanian, T.S., Golden, J.W. J. Bacteriol. (1994) [Pubmed]
  3. General distribution of the nitrogen control gene ntcA in cyanobacteria. Frías, J.E., Mérida, A., Herrero, A., Martín-Nieto, J., Flores, E. J. Bacteriol. (1993) [Pubmed]
  4. Mutual dependence of the expression of the cell differentiation regulatory protein HetR and the global nitrogen regulator NtcA during heterocyst development. Muro-Pastor, A.M., Valladares, A., Flores, E., Herrero, A. Mol. Microbiol. (2002) [Pubmed]
  5. Requirement of the regulatory protein NtcA for the expression of nitrogen assimilation and heterocyst development genes in the cyanobacterium Anabaena sp. PCC 7120. Frías, J.E., Flores, E., Herrero, A. Mol. Microbiol. (1994) [Pubmed]
  6. Anabaena sp. strain PCC 7120 bifA gene encoding a sequence-specific DNA-binding protein cloned by in vivo transcriptional interference selection. Wei, T.F., Ramasubramanian, T.S., Pu, F., Golden, J.W. J. Bacteriol. (1993) [Pubmed]
  7. Transcription of the Anabaena sp. strain PCC 7120 ntcA gene: multiple transcripts and NtcA binding. Ramasubramanian, T.S., Wei, T.F., Oldham, A.K., Golden, J.W. J. Bacteriol. (1996) [Pubmed]
  8. HetR-dependent and -independent expression of heterocyst-related genes in an Anabaena strain overproducing the NtcA transcription factor. Olmedo-Verd, E., Flores, E., Herrero, A., Muro-Pastor, A.M. J. Bacteriol. (2005) [Pubmed]
  9. The hetC gene is a direct target of the NtcA transcriptional regulator in cyanobacterial heterocyst development. Muro-Pastor, A.M., Valladares, A., Flores, E., Herrero, A. J. Bacteriol. (1999) [Pubmed]
  10. Vectors for determining the differential expression of genes in heterocysts and vegetative cells of Anabaena sp. strain PCC 7120. Bauer, C.C., Haselkorn, R. J. Bacteriol. (1995) [Pubmed]
  11. Expression of furA is modulated by NtcA and strongly enhanced in heterocysts of Anabaena sp. PCC 7120. L??pez-Gomoll??n, S., Hern??ndez, J.A., Wolk, C.P., Peleato, M.L., Fillat, M.F. Microbiology (Reading, Engl.) (2007) [Pubmed]
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