Group 3 sigma factor gene, sigJ, a key regulator of desiccation tolerance, regulates the synthesis of extracellular polysaccharide in cyanobacterium Anabaena sp. strain PCC 7120

Yoshimura, Hidehisa; Okamoto, Shinobu; Tsumuraya, Yoichi; Ohmori, Masayuki

doi:10.1093/dnares/dsm003

Cited by 59 publications

(51 citation statements)

References 46 publications

(36 reference statements)

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“…Besides the principal, group 1 factor SigA, multiple alternative group 2 factors have been identified in the several cyanobacteria investigated to date (6,26,55). In the unicellular cyanobacterium Synechocystis sp.…”

Section: Resultsmentioning

confidence: 99%

Transcription Activation by NtcA and 2-Oxoglutarate of Three Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120

2008

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In Anabaena sp. strain PCC 7120, differentiation of heterocysts takes place in response to the external cue of combined nitrogen deprivation, allowing the organism to fix atmospheric nitrogen in oxic environments. NtcA, a global transcriptional regulator of cyanobacteria, is required for activation of the expression of multiple genes involved in heterocyst differentiation, including key regulators that are specific to the process. We have set up a fully defined in vitro system, which includes the purified Anabaena RNA polymerase, and have studied the effects of NtcA and its signaling effector 2-oxoglutarate on RNA polymerase binding, open complex formation, and transcript production from promoters of the hetC, nrrA, and devB genes that are activated by NtcA at different stages of heterocyst differentiation. Both RNA polymerase and NtcA could specifically bind to the target DNA in the absence of any effector. 2-Oxoglutarate had a moderate positive effect on NtcA binding, and NtcA had a limited positive effect on RNA polymerase recruitment at the promoters. However, a stringent requirement of both NtcA and 2-oxoglutarate was observed for the detection of open complexes and transcript production at the three investigated promoters. These results support a key role for 2-oxoglutarate in transcription activation in the developing heterocyst.

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Section: Resultsmentioning

confidence: 99%

Transcription Activation by NtcA and 2-Oxoglutarate of Three Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120

2008

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“…strain PCC 7120 (here Anabaena PCC 7120) sigE gene (alr4249; previously called sigF), which encodes a group 2 70 family sigma factor, is required for the normal expression of some genes involved in heterocyst development. (We follow the revised nomenclature of Yoshimura et al for cyanobacterial sigma factor names [3,58].) The expression of sigE in the unicellular cyanobacterium Synechocystis sp.…”

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confidence: 99%

“…A sigB2 sigD double mutant can form proheterocysts but is unable to grow diazotrophically, possibly due to extensive fragmentation of filaments upon nitrogen deprivation (27). The failure to find any single sigma factor that is essential for heterocyst development suggests that the cyanobacterial group 2 sigma factors have partially overlapping functions, which has hampered genetic analysis (3,27,32,39,58).…”

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confidence: 99%

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

et al. 2011

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The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 produces specialized cells for nitrogen fixation called heterocysts. Previous work showed that the group 2 sigma factor sigE (alr4249; previously called sigF) is upregulated in differentiating heterocysts 16 h after nitrogen step-down. We now show that the sigE gene is required for normal heterocyst development and normal expression levels of several heterocyst-specific genes. Mobility shift assays showed that the transcription factor NtcA binds to sites in the upstream region of sigE and that this binding is enhanced by 2-oxoglutarate (2-OG). Deletions of the region containing the NtcA binding sites in P sigE -gfp reporter plasmids showed that the sites contribute to normal developmental regulation but are not essential for upregulation in heterocysts. Northern RNA blot analysis of nifH mRNA revealed delayed and reduced transcript levels during heterocyst differentiation in a sigE mutant background. Quantitative reverse transcription-PCR (qRT-PCR) analyses of the sigE mutant showed lower levels of transcripts for nifH, fdxH, and hglE2 but normal levels for hupL. We developed a P nifHD -gfp reporter construct that showed strong heterocyst-specific expression. Time-lapse microscopy of the P nifHD -gfp reporter in a sigE mutant background showed delayed development and undetectable green fluorescent protein (GFP) fluorescence. Overexpression of sigE caused accelerated heterocyst development, an increased heterocyst frequency, and premature expression of GFP fluorescence from the P nifHD -gfp reporter.

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“…The production of EPS is widely known in cyanobacteria (Kehr and Dittmann, 2015;Pereira et al, 2009), and it is believed that EPS in cyanobacteria play a role in protecting cells from various stresses within severe habitats (Chakraborty and Pal, 2014;Ehling-Schulz et al, 1997;Yoshimura et al, 2007). In its natural habitats, N. commune forms visually conspicuous colonies that consist of an extracellular matrix with filamentous cells embedded inside (Helm and Potts, 2012;Potts, 2000).…”

Section: Introductionmentioning

confidence: 99%

Characterization of extracellular matrix components from the desiccation-tolerant cyanobacterium <i>Nostoc commune</i>

Inoue-Sakamoto

Tanji

Yamaba

et al. 2018

J. Gen. Appl. Microbiol.

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The terrestrial cyanobacterium Nostoc commune forms macroscopic colonies in its natural habitats, and these colonies consist of both cellular filaments and massive extracellular matrixes. In this study, the biochemical features of the extracellular matrix components were investigated. Naturally growing N. commune was tolerant to desiccation, and produced massive extracellular polysaccharides that contained both neutral sugars and glucuronic acid as constituent monosaccharides. The extracellular polysaccharide contents and desiccation tolerance were compared in laboratory culture strains of Nostoc species. The laboratory culture of N. commune strain KU002 was sensitive to desiccation and produced smaller amounts of extracellular polysaccharides, unlike the field-isolated naturally growing colonies. Nostoc punctiforme strain M-15, which is genetically closed to N. commune, was able to tolerate desiccation, although the other Nostoc strains were desiccation-sensitive. A laboratory culture strain of the aquatic cyanobacterium Nostoc sphaericum produced massive extracellular polysaccharides but was sensitive to desiccation, suggesting that extracellular matrix production is not enough to make this strain tolerant to desiccation. WspA (water stress protein) and SodF (superoxide dismutase) were found to be characteristic protein components of the extracellular matrix of N. commune. Because the WspA proteins were heterogeneous, the wspA genes were highly diverse among the different genotypes of N. commune, although the sodF gene was rather conservative. The heterogeneity of the WspA proteins suggests their complex roles in the environmental adaptation mechanism in N. commune.

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Group 3 sigma factor gene, sigJ, a key regulator of desiccation tolerance, regulates the synthesis of extracellular polysaccharide in cyanobacterium Anabaena sp. strain PCC 7120

Cited by 59 publications

References 46 publications

Transcription Activation by NtcA and 2-Oxoglutarate of Three Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120

Transcription Activation by NtcA and 2-Oxoglutarate of Three Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

Characterization of extracellular matrix components from the desiccation-tolerant cyanobacterium <i>Nostoc commune</i>

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