Transcription of the Anabaena sp. strain PCC 7120 ntcA gene: multiple transcripts and NtcA binding

Ramasubramanian, T.; Wei, Tingcun; Oldham, A. K.; Golden, James W.

doi:10.1128/jb.178.3.922-926.1996

Cited by 81 publications

(87 citation statements)

References 22 publications

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“…The ntcA expression pattern with high transcript levels in the presence of ammonium as presented here for Trichodesmium is also encountered in the N 2 fixers Cyanothece and Anabaena (Ramasubramanian et al, 1996;Bradley and Reddy, 1997). The latter produces three different transcripts, two of which seem to originate from an atypical promoter that involves NtcA binding (Ramasubramanian et al, 1996). Thus, ntcA may be involved in the development of nitrate utilization as its expression is high both in nitrate-grown Trichodesmium IMS101 (this study) and in Cyanothece BH68K (Bradley and Reddy, 1997).…”

Section: Transcriptional Regulationmentioning

confidence: 81%

“…and thus yields two transcript populations, the latter one regulated by NtcA (Luque et al, 1994;Lindell et al, 1998). The ntcA expression pattern with high transcript levels in the presence of ammonium as presented here for Trichodesmium is also encountered in the N 2 fixers Cyanothece and Anabaena (Ramasubramanian et al, 1996;Bradley and Reddy, 1997). The latter produces three different transcripts, two of which seem to originate from an atypical promoter that involves NtcA binding (Ramasubramanian et al, 1996).…”

Section: Transcriptional Regulationmentioning

confidence: 90%

“…Two ORFs (ORF5 and ORF6) immediately downstream of ntcA were in the same orientation as ntcA (Figure 4). ORF5 was first identified in Anabaena PCC 7120 (Ramasubramanian et al, 1994(Ramasubramanian et al, , 1996 and ntcA-ORF5 form a conserved gene pair in nearly all cyanobacteria (AF Post, unpublished data). As no clear promoter elements were identifiable upstream of ORF5, we studied the transcription of ntcA and ORF5 by RT-PCR.…”

Section: Nitrogen Physiologymentioning

confidence: 99%

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Decoupling of ammonium regulation and ntcA transcription in the diazotrophic marine cyanobacterium Trichodesmium sp. IMS101

2011

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Nitrogen (N) physiology in the marine cyanobacterium Trichodesmium IMS101 was studied along with transcript accumulation of the N-regulatory gene ntcA and of two of its target genes: napA (nitrate assimilation) and nifH (N 2 fixation). N 2 fixation was impaired in the presence of nitrite, nitrate and urea. Strain IMS101 was capable of growth on these combined N sources at o2 lM but growth rates declined at elevated concentrations. Assimilation of nitrate and urea was impaired in the presence of ammonium. Whereas ecologically relevant N concentrations (2-20 lM) suppressed growth and assimilation, much higher concentrations were required to affect transcript levels. Transcripts of nifH accumulated under nitrogen-fixing conditions; these transcript levels were maintained in the presence of nitrate (100 lM) and ammonium (20 lM). However, nifH transcript levels were below detection at ammonium concentrations 420 lM. napA mRNA was found at low levels in both N 2 -fixing and ammonium-utilizing filaments, and it accumulated in filaments grown with nitrate. The positive effect of nitrate on napA transcription was abolished by ammonium additions of 4200 lM. This effect was restored upon addition of the glutamine synthetase inhibitor L-methionin-DL-sulfoximine. Surprisingly, ntcA transcript levels remained high in the presence of ammonium, even at elevated concentrations. These findings indicate that ammonium repression is decoupled from transcriptional activation of ntcA in Trichodesmium IMS101.

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Section: Transcriptional Regulationmentioning

confidence: 81%

Section: Transcriptional Regulationmentioning

confidence: 90%

Section: Nitrogen Physiologymentioning

confidence: 99%

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Decoupling of ammonium regulation and ntcA transcription in the diazotrophic marine cyanobacterium Trichodesmium sp. IMS101

2011

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“…Any remaining traces of oxygen, and any that diffuses into the cell along with N # , are removed by several mechanisms, the most important of which is probably respiration. Because they lack Rubisco, heterocysts do not fix Wei et al, 1993Ramasubramanian et al, 1994Ramasubramanian et al, , 1996Jiang et al, 1997 In row H (homology), ' None ' indicates that no homology has been found to any known proteins in the databases. Abbreviations : MCH, multiple contiguous heterocysts ; MCP, multiple contiguous heterocysts ; ND, not determined.…”

Section: Function and Metabolismmentioning

confidence: 99%

Tansley Review No. 107. Heterocyst and akinete differentiation in cyanobacteria

1999

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“…1). It has been demonstrated in PCC 7942 and PCC 7120 that NtcA binds to the promoter region of and activates genes involved in nitrogen control such as glnA, nir, and ntcA itself (3,9,12,13). Given its similarity to the NtcA proteins from PCC 7942 and PCC 7120, it is possible that the Cyanothece NtcA protein may bind similar target sequences.…”

mentioning

confidence: 99%

Cloning, sequencing, and regulation of the global nitrogen regulator gene ntcA in the unicellular diazotrophic cyanobacterium Cyanothece sp. strain BH68K

Bradley

Reddy

1997

J Bacteriol

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In cyanobacteria, ammonium represses expression of proteins involved in nitrogen fixation and assimilation. The global nitrogen regulator gene ntcA encodes a DNA-binding protein, NtcA, that is a transcriptional activator of genes subject to nitrogen control. We report the cloning and sequencing of the ntcA gene from a nitrogen-fixing unicellular cyanobacterium, Cyanothece sp. strain BH68K. The gene comprises 678 nucleotides, and the deduced NtcA protein contains 226 amino acids with a predicted molecular weight of 25,026. In addition, ntcA mRNA levels were measured in cells grown under different nitrogen regimes. Under nitrogenfixing conditions, ntcA transcripts were weakly expressed. Furthermore, ntcA expression was diminished or inversely proportional to nifHDK expression. Conversely, ntcA expression increased in nitrate-grown cells, and a concentration-dependent increase was seen in ammonium-grown cells up to 1 mM NH 4 Cl. These results indicate that ntcA is involved more in nitrogen assimilation than in nitrogen fixation and also imply that the rhythmic expression of ntcA and nifHDK transcription may be under the control of a circadian clock.

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Transcription of the Anabaena sp. strain PCC 7120 ntcA gene: multiple transcripts and NtcA binding

Cited by 81 publications

References 22 publications

Decoupling of ammonium regulation and ntcA transcription in the diazotrophic marine cyanobacterium Trichodesmium sp. IMS101

Decoupling of ammonium regulation and ntcA transcription in the diazotrophic marine cyanobacterium Trichodesmium sp. IMS101

Tansley Review No. 107. Heterocyst and akinete differentiation in cyanobacteria

Cloning, sequencing, and regulation of the global nitrogen regulator gene ntcA in the unicellular diazotrophic cyanobacterium Cyanothece sp. strain BH68K

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