CalA, a cyAbrB protein, binds to the upstream region of ftsZ and is down-regulated in heterocysts in Anabaena sp. PCC 7120

He, Dongli; Xu, Xudong

doi:10.1007/s00203-010-0573-9

Cited by 14 publications

(18 citation statements)

References 34 publications

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“…The functions of CalA and CalB in cyanobacteria are largely unknown, but parts of it are starting to be revealed. CalA appears to be essential, since no attempts to create a fully segregated knock-out mutant have been successful [37,44], and have been shown to interact with the promoter regions of genes involved in hydrogen metabolism in Nostoc PCC 7120 [34] and Synechocystis PCC 6803 [37], toxin production in Aphanizomenon ovalisporum [48], and with the promoter regions of FtsZ [49] and FeSOD in Nostoc PCC 7120 [50]. Fully segregated knock-out mutants of CalB have, however, been constructed in Synechocystis PCC 6803 [44] and it appears to play an important role in the regulation of genes involved in nitrogen uptake [44] and carbon concentrating mechanisms [51].…”

Section: Discussionmentioning

confidence: 99%

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

et al. 2011

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BackgroundCyanobacteria harbor two [NiFe]-type hydrogenases consisting of a large and a small subunit, the Hup- and Hox-hydrogenase, respectively. Insertion of ligands and correct folding of nickel-iron hydrogenases require assistance of accessory maturation proteins (encoded by the hyp-genes). The intergenic region between the structural genes encoding the uptake hydrogenase (hupSL) and the accessory maturation proteins (hyp genes) in the cyanobacteria Nostoc PCC 7120 and N. punctiforme were analysed using molecular methods.FindingsThe five ORFs, located in between the uptake hydrogenase structural genes and the hyp-genes, can form a transcript with the hyp-genes. An identical genomic localization of these ORFs are found in other filamentous, N2-fixing cyanobacterial strains. In N. punctiforme and Nostoc PCC 7120 the ORFs upstream of the hyp-genes showed similar transcript level profiles as hupS (hydrogenase structural gene), nifD (nitrogenase structural gene), hypC and hypF (accessory hydrogenase maturation genes) after nitrogen depletion. In silico analyzes showed that these ORFs in N. punctiforme harbor the same conserved regions as their homologues in Nostoc PCC 7120 and that they, like their homologues in Nostoc PCC 7120, can be transcribed together with the hyp-genes forming a larger extended hyp-operon. DNA binding studies showed interactions of the transcriptional regulators CalA and CalB to the promoter regions of the extended hyp-operon in N. punctiforme and Nostoc PCC 7120.ConclusionsThe five ORFs upstream of the hyp-genes in several filamentous N2-fixing cyanobacteria have an identical genomic localization, in between the genes encoding the uptake hydrogenase and the maturation protein genes. In N. punctiforme and Nostoc PCC 7120 they are transcribed as one operon and may form transcripts together with the hyp-genes. The expression pattern of the five ORFs within the extended hyp-operon in both Nostoc punctiforme and Nostoc PCC 7120 is similar to the expression patterns of hupS, nifD, hypF and hypC. CalA, a known transcription factor, interacts with the promoter region between hupSL and the five ORFs in the extended hyp-operon in both Nostoc strains.

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Section: Discussionmentioning

confidence: 99%

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

et al. 2011

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“…The mixture was incubated at 25°C for 20 min and separated by electrophoresis with 4% nondenaturing polyacrylamide gel at 4°C. Labeled DNA fragments were then transferred onto Hybond-N ϩ membrane and visualized as previously described (15).…”

Section: Methodsmentioning

confidence: 99%

Identification of the HetR Recognition Sequence Upstream of hetZ in Anabaena sp. Strain PCC 7120

Cai

Hou

et al. 2012

J Bacteriol

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HetR is the master regulator of heterocyst differentiation in Anabaena sp. strain PCC 7120 and has been found to specifically bind to an inverted-repeat-containing region upstream of hetP, a heterocyst differentiation gene. However, no such invertedrepeat sequence can be found in promoters of other genes in the genome. hetZ is a gene involved in early heterocyst differentiation. As shown with the gfp reporter gene, transcription from P hetZ was correlated to the expression level of hetR and inhibition by RGSGR, the pentapeptide derived from the C terminus of PatS. As detected by electrophoretic mobility shift assay, a recombinant HetR showed specific binding to the region upstream of hetZ, and the binding was inhibited by RGSGR. Tests of a series of the upstream fragments delimited the HetR-binding site to a 40-bp region that shows similarity to that upstream of hetP. The introduction of substitutions of bases conserved in the two HetR-binding sites showed that at least 12 bases are required for recognition by HetR. Deletion of a 51-bp region containing the HetR-binding site completely eliminated the transcription activity of P hetZ . Based on the HetR recognition sequence of hetZ, those upstream of hetR and patA are proposed.

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“…Furthermore, cyAbrBs have been reported to bind to the upstream regions of nitrogen-regulated genes (9), of sbtA encoding a Na ϩ /HCO 3 Ϫ symporter in Synechocystis sp. strain PCC 6803 (10), of hypC involved in the maturation of hydrogenase (1), of ftsZ encoding a key cell division protein (7), and of sodB encoding iron superoxide dismutase (2) in Nostoc sp. strain PCC 7120.…”

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“…strain PCC 6803 (9,16) and in Nostoc sp. strain PCC 7120 (1,7). This suggests that clade A members are important for cell viability and that their functions cannot be supplied by the remaining clade B members.…”

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Physiological Roles of the cyAbrB Transcriptional Regulator Pair Sll0822 and Sll0359 in Synechocystis sp. strain PCC 6803

et al. 2011

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All known cyanobacterial genomes possess multiple copies of genes encoding AbrB-like transcriptional regulators, known as cyAbrBs, which are distinct from those conserved among other bacterial species. In this study, we addressed the physiological roles of Sll0822 and Sll0359, the two cyAbrBs in Synechocystis sp. strain PCC 6803, under nonstress conditions (20 mol of photons m ؊2 s ؊1 in ambient CO 2 ). When the sll0822 gene was disrupted, the expression levels of nitrogen-related genes such as urtA, amt1, and glnB significantly decreased compared with those in the wild-type cells. Possibly due to the increase of the cellular carbon/ nitrogen ratio in the sll0822-disrupted cells, a decrease in pigment contents, downregulation of carbon-uptake related genes, and aberrant accumulation of glycogen took place. Moreover, the mutant exhibited the decrease in the expression level of cytokinesis-related genes such as ftsZ and ftsQ, resulting in the defect in cell division and significant increase in cell size. The pleiotrophic phenotype of the mutant was efficiently suppressed by the introduction of Sll0822 and also partially suppressed by the introduction of Sll0359. When His-tagged cyAbrBs were purified from overexpression strains, Sll0359 and Sll0822 were copurified with each other. The cyAbrBs in Synechocystis sp. strain PCC 6803 seem to interact with each other and regulate carbon and nitrogen metabolism as well as the cell division process under nonstress conditions.All known cyanobacterial genomes possess multiple copies of genes encoding putative transcriptional regulators having an AbrB-type DNA binding domain. cyAbrBs are structurally different from AbrB-type regulators widely conserved among other bacterial species (4, 25) in that they have a DNA binding domain in the C-terminal region instead of in the usual N-terminal region (9). To date, several research groups have reported the identification of cyAbrBs as binding factors to the upstream region of their target genes. By DNA affinity precipitation assay, Onizuka et al. (17) have identified binding of a cyAbrB to the upstream region of the rbc operon encoding the ribulose-1,5-bisphosphate carboxylase/oxygenase in Synechococcus sp. strain PCC 7002. Similarly, by DNA affinity assay, Oliveira and Lindblad (16) have isolated a cyAbrB as a binding factor to the upstream region of the hox operon encoding the bidirectional NiFe hydrogenase in Synechocystis sp. strain PCC 6803. Shalev-Malul et al. (22) have identified specific binding of a cyAbrB to the intergenic region between aoaA and aoaC encoding biosynthetic enzymes for the hepatotoxin cylindrospermopsin in Aphanizomenon ovalisporum. Furthermore, cyAbrBs have been reported to bind to the upstream regions of nitrogen-regulated genes (9), of sbtA encoding a Na ϩ /HCO 3 Ϫ symporter in Synechocystis sp. strain PCC 6803 (10), of hypC involved in the maturation of hydrogenase (1), of ftsZ encoding a key cell division protein (7), and of sodB encoding iron superoxide dismutase (2) in Nostoc sp. strain PCC 7120. It ...

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CalA, a cyAbrB protein, binds to the upstream region of ftsZ and is down-regulated in heterocysts in Anabaena sp. PCC 7120

Cited by 14 publications

References 34 publications

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

Identification of the HetR Recognition Sequence Upstream of hetZ in Anabaena sp. Strain PCC 7120

Physiological Roles of the cyAbrB Transcriptional Regulator Pair Sll0822 and Sll0359 in Synechocystis sp. strain PCC 6803

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