Characterization of a nitrogen-fixation (nif) gene cluster from Anabaena azollae 1a shows that closely related cyanobacteria have highly variable but structured intergenic regions

Jackman, Donna M.; Mulligan, Martin E.

doi:10.1099/13500872-141-9-2235

Cited by 28 publications

(35 citation statements)

References 33 publications

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“…Consistently, it is not expressed in the ntcA [8] and hetR (our unpublished results) mutants. The nifH tsp that we have detected with RNA isolated from either whole ¢laments or heterocysts is localized essentially at the position previously reported [27] and is close to the tsp described for Anabaena azollae nifH [33]. A putative 310 box might be recognized in this promoter (Fig.…”

Section: Discussionmentioning

confidence: 85%

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

et al. 1999

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Determination of the putative transcription start points of the petH gene encoding ferredoxin:NADP reductase in the heterocyst-forming cyanobacteria Anabaena sp. PCC 7119 and PCC 7120 showed that this gene is transcribed from two promoters, one constitutively used under different conditions of nitrogen nutrition and the other one used in cells subjected to nitrogen stepdown and in nitrogen-fixing filaments. The latter promoter, whose use was NtcA-dependent but HetR-independent, was functional in heterocysts. The N-control transcriptional regulator NtcA was observed to bind in vitro to this promoter. For the sake of comparison, the transcription start points of the nifHDK operon in strain PCC 7120 and binding of NtcA to the nifHDK promoter were also examined.z 1999 Federation of European Biochemical Societies.

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Section: Discussionmentioning

confidence: 85%

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

et al. 1999

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“…PCC 7120 and A. azollae have almost identical sequences upstream of nifH as shown in Fig. 3 (Jackman & Mulligan, 1995;Mulligan & Haselkorn, 1989) but the proposed transcription start sites differ by at least six bases (Turner et al, 1983;Haselkorn et al, 1983;Mulligan & Haselkorn, 1989 ;Jackman & Mulligan, 1995). Significant identities were observed between the sequence .,,TAATAC.,, for Trichodesmiurn sp.…”

Section: Aaaacattaatcacaattttat -Atmentioning

confidence: 98%

“…The uppermost (longest) primer extension product (indicated by an arrow) corresponded to the same nucleotide (A), indicated by an asterisk, for all three primers. (Jackman & Mulligan, 1995). The consensus -10 and -35 promoter elements are indicated by bold lines.…”

Section: Discussionmentioning

confidence: 99%

Cloning and transcriptional analysis of the nifUHDK genes of Trichodesmium sp. IMS101 reveals stable nifD, nifDK and nifK transcripts

Dominic¹,

Chen²,

Zehr³

1998

Microbiology

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Trichodesmium spp. are marine filamentous, non-heterocystous cyanobacteria capable of aerobic nitrogen fixation. In this study, the nitrogenase structural genes (nifHDK) and nifU gene of Trichodesmium sp. I M S l O l were cloned and sequenced. The Trichodesmium sp. I M S l O l nifH, nifD and nifK amino acid sequences showed only 79%, 66% and 68% identity, respectively, to those of Anabaena sp. strain PCC 7120. A potential transcription start site for nifH was found 212 bases upstream of the nifH start codon. Promoter-like nucleotide sequences upstream of the transcription start site were identified that were very similar to those identified for the nitrogenase genes of Anabaena spp. Sequence analysis revealed regions of DNA that may form stem-loop structures in the intercistronic regions downstream of nifH and nifD, RNA analysis by Northern hybridization revealed the presence of transcripts corresponding to nifH, nifHD and nifHDK. Surprisingly, Northern hybridization also revealed the presence of transcripts that corresponded to nifD, nifDK and nifK, which have not been previously reported as transcripts in contiguous nifHDK genes of cyanobacteria. Transcription of the nifHDK genes was not significantly repressed in the presence of nitrate a t a final concentration of 20 mM or a t oxygen concentrations of up to 40%, whereas ammonium and urea inhibited nifHDK transcription. The transcription of the nifHDK genes was not affected by darkness, which suggests that transcription of these genes in Trichodesmium is not directly regulated by light.

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Section: Two Different Its Regions (Its-l and Its-s)mentioning

confidence: 99%

“…STRR sequences appear to be common in heterocystous cyanobacteria, where they occur primarily, though not exclusively, in intergenic regions (Jackman & Mulligan, 1995 ;Mazel et al, 1990 ;Vioque, 1997), but they are rarely paired with a complementary sequence and have not been reported previously in the rrn operon. At least nine different STRR families are known (Jackman & Mulligan, 1995). The Nostoc PCC 7120 STRR sequences within the ITS are similar to STRR type 6 sequences that form a similar structure (Vioque, 1997) within the Rnase P transcript of another Nostoc strain, PCC 7937 (Anabaena ATCC 29413), but differ from those found (Mazel et al, 1990) elsewhere in the Nostoc PCC 7120 genome.…”

Section: Two Different Its Regions (Its-l and Its-s)mentioning

confidence: 99%

Comparison of conserved structural and regulatory domains within divergent 16S rRNA–23S rRNA spacer sequences of cyanobacteria The GenBank accession numbers for the sequences reported in this paper are AF180968 and AF180969 for ITS-L and ITS-S, respectively.

et al. 2000

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PCR amplification of the internal transcribed spacer (ITS) between the 16SrRNA and 23S rRNA genes of the cyanobacterium Nostoc PCC 7120 gave three products. Two represented true ITS regions of different sizes, while the third was a heteroduplex. The longer spacer (ITS-L) contained 512 nucleotides and carried tRNA Ile and tRNA Ala genes, separated by a large stem-loop structure (V2) composed of short tandemly repeated repetitive sequences. Both tRNA genes, and the 5' half of the intervening stem, were absent from the shorter spacer (ITS-S), of length 283 nucleotides, which was otherwise almost completely identical to ITS-L. The two spacer regions of Nostoc PCC 7120 were aligned to published ITS sequences of cyanobacteria, the cyanelle of Cyanophora paradoxa and Escherichia coli. Although the ITS regions of cyanobacteria vary in length from 283 to 545 nucleotides and contain either both tRNA Ile and tRNA Ala genes, only the tRNA Ile gene, or neither, there is no correlation between ITS size and coding capacity for tRNAs. Putative secondary structures were determined for the deduced transcripts of the rrn operons of several cyanobacteria and were compared to that of E. coli. Highly conserved motifs important for folding and for maturation of the rRNA transcripts were identified, and regions homologous to bacterial antiterminators (box B-box A) were located. The conserved and variable regions of the cyanobacterial ITS are potential targets of PCR primers and oligonucleotide probes for detection and identification of cyanobacteria at different taxonomic levels.

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Characterization of a nitrogen-fixation (nif) gene cluster from Anabaena azollae 1a shows that closely related cyanobacteria have highly variable but structured intergenic regions

Cited by 28 publications

References 33 publications

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

Cloning and transcriptional analysis of the nifUHDK genes of Trichodesmium sp. IMS101 reveals stable nifD, nifDK and nifK transcripts

Comparison of conserved structural and regulatory domains within divergent 16S rRNA–23S rRNA spacer sequences of cyanobacteria The GenBank accession numbers for the sequences reported in this paper are AF180968 and AF180969 for ITS-L and ITS-S, respectively.

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Characterization of a nitrogen-fixation (nif) gene cluster from Anabaena azollae 1a shows that closely related cyanobacteria have highly variable but structured intergenic regions

Cited by 28 publications

References 33 publications

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP+ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP+ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

Cloning and transcriptional analysis of the nifUHDK genes of Trichodesmium sp. IMS101 reveals stable nifD, nifDK and nifK transcripts

Comparison of conserved structural and regulatory domains within divergent 16S rRNA–23S rRNA spacer sequences of cyanobacteria The GenBank accession numbers for the sequences reported in this paper are AF180968 and AF180969 for ITS-L and ITS-S, respectively.

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Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp

Constitutive and nitrogen‐regulated promoters of the petH gene encoding ferredoxin:NADP⁺ reductase in the heterocyst‐forming cyanobacterium Anabaena sp