Genome-wide Expression Analysis of the Responses to Nitrogen Deprivation in the Heterocyst-forming Cyanobacterium Anabaena sp. Strain PCC 7120

ABSTRACT Heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120 requires NtcA, the global nitrogen regulator in cyanobacteria, and HetR, the master regulator of heterocyst differentiation. Expression of hetR is upregulated by nitrogen deprivation, and its upregulation depends on NtcA. However, it has not yet been revealed how NtcA regulates the expression of hetR. In the experiments presented here, it was confirmed that NrrA (All4312), a nitrogen-responsive response regulator, was required for the upregulation of hetR. The use of the nitrogen-responsive transcription initiation sites (TISs) for the hetR gene depended upon NrrA. NrrA bound specifically to the region upstream of TISs located at positions −728 and −696 in vitro. Overexpression of nrrA resulted in enhanced hetR expression and heterocyst formation. A molecular regulatory cascade is proposed whereby NtcA upregulates the expression of nrrA upon limitation of combined nitrogen in the medium and then NrrA upregulates the expression of hetR, leading to heterocyst differentiation.

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The Ser/Thr Kinase PknH Is Essential for Maintaining Heterocyst Pattern in the Cyanobacterium Anabaena sp. Strain PCC 7120

Life ◽

10.3390/life8030034 ◽

2018 ◽

Vol 8 (3) ◽

pp. 34 ◽

Cited By ~ 6

Author(s):

Shun-ichi Fukushima ◽

Shigeki Ehira

Keyword(s):

Pattern Formation ◽

Lateral Inhibition ◽

Time Lapse ◽

Filamentous Cyanobacterium ◽

Nitrogen Deprivation ◽

Heterocyst Differentiation ◽

Cyanobacterium Anabaena ◽

Reporter Strains ◽

Anabaena Sp ◽

Pcc 7120

In the filamentous cyanobacterium Anabaena sp. strain, PCC 7120, heterocysts (which are nitrogen-fixing cells) are formed in the absence of combined nitrogen in the medium. Heterocysts are separated from one another by 10 to 15 vegetative cells along the filaments, which consist of a few hundred of cells. hetR is necessary for heterocyst differentiation; and patS and hetN, expressed in heterocysts, play important roles in heterocyst pattern formation by laterally inhibiting the expression of hetR in adjacent cells. The results of this study indicated that pknH, which encodes a Ser/Thr kinase, was also involved in heterocyst pattern formation. In the pknH mutant, the heterocyst pattern was normal within 24 h after nitrogen deprivation, but multiple contiguous heterocysts were formed from 24 to 48 h. A time-lapse analysis of reporter strains harboring a fusion between gfp and the hetR promoter indicated that pknH was required to suppress hetR expression in cells adjacent to the preexisting heterocysts. These results indicated that pknH was necessary for the lateral inhibition of heterocyst differentiation to maintain the heterocyst pattern.

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NrrA directly regulates expression of the fraF gene and antisense RNAs for fraE in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120

Microbiology ◽

10.1099/mic.0.076703-0 ◽

2014 ◽

Vol 160 (5) ◽

pp. 844-850 ◽

Cited By ~ 5

Author(s):

Shigeki Ehira ◽

Masayuki Ohmori

Keyword(s):

Response Regulator ◽

Repeat Sequence ◽

Nitrogen Deprivation ◽

Antisense Rnas ◽

Regulated Expression ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Dna Strand ◽

Pcc 7120 ◽

Diazotrophic Growth

The heterocystous cyanobacterium Anabaena sp. strain PCC 7120 grows as linear multicellular filaments that can contain hundreds of cells. Heterocysts, which are specialized cells for nitrogen fixation, are regularly intercalated among photosynthetic vegetative cells, and these cells are metabolically dependent on each other. Thus, multicellularity is essential for diazotrophic growth of heterocystous cyanobacteria. In Anabaena sp. strain PCC 7120, the fraF gene, which is required to limit filament length, is induced by nitrogen deprivation. The fraF transcripts extend to the fraE gene, which lies on the opposite DNA strand and could possess dual functionality, mRNAs for fraF and antisense RNAs for fraE. In the present study, we found that NrrA, a nitrogen-regulated response regulator, directly regulated expression of fraF. Induction of fraF by nitrogen deprivation was abolished by the nrrA disruption. NrrA specifically bound to the promoter region of fraF, and recognized an inverted repeat sequence. Thus, it is concluded that NrrA controls expression of mRNAs for fraF and antisense RNAs for fraE in response to nitrogen deprivation.

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Genome-Wide and Heterocyst-Specific Circadian Gene Expression in the Filamentous Cyanobacterium Anabaena sp. Strain PCC 7120

Journal of Bacteriology ◽

10.1128/jb.02067-12 ◽

2013 ◽

Vol 195 (6) ◽

pp. 1276-1284 ◽

Cited By ~ 10

Author(s):

H. Kushige ◽

H. Kugenuma ◽

M. Matsuoka ◽

S. Ehira ◽

M. Ohmori ◽

...

Keyword(s):

Gene Expression ◽

Filamentous Cyanobacterium ◽

Circadian Gene ◽

Genome Wide ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120

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Genome wide expression analysis of the effect of Pinelliae Rhizoma extract on psychological stress

Planta Medica ◽

10.1055/s-0030-1264921 ◽

2010 ◽

Vol 76 (12) ◽

Author(s):

S Cho ◽

C Lim ◽

H Kim

Keyword(s):

Psychological Stress ◽

Expression Analysis ◽

Genome Wide ◽

Genome Wide Expression

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Expanding the Natural Products Heterologous Expression Repertoire in the Model Cyanobacterium Anabaena sp. Strain PCC 7120: Production of Pendolmycin and Teleocidin B-4

10.26434/chemrxiv.11316098.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Patrick Videau ◽

Kaitlyn Wells ◽

Arun Singh ◽

Jessie Eiting ◽

Philip Proteau ◽

...

Keyword(s):

Natural Products ◽

Genome Mining ◽

Gene Clusters ◽

Combinatorial Biosynthesis ◽

Test Case ◽

Biosynthetic Gene ◽

Biosynthetic Gene Clusters ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120

Cyanobacteria are prolific producers of natural products and genome mining has shown that many orphan biosynthetic gene clusters can be found in sequenced cyanobacterial genomes. New tools and methodologies are required to investigate these biosynthetic gene clusters and here we present the use of <i>Anabaena </i>sp. strain PCC 7120 as a host for combinatorial biosynthesis of natural products using the indolactam natural products (lyngbyatoxin A, pendolmycin, and teleocidin B-4) as a test case. We were able to successfully produce all three compounds using codon optimized genes from Actinobacteria. We also introduce a new plasmid backbone based on the native <i>Anabaena</i>7120 plasmid pCC7120ζ and show that production of teleocidin B-4 can be accomplished using a two-plasmid system, which can be introduced by co-conjugation.

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