NrrA, a Nitrogen-regulated Response Regulator Protein, Controls Glycogen Catabolism in the Nitrogen-fixing Cyanobacterium Anabaena sp. Strain PCC 7120

Abstract

Background: Carbohydrate catabolism provides the energy for nitrogen fixation in filamentous cyanobacteria. Results: A nitrogen-regulated response regulator NrrA controlled glycogen catabolism in the filamentous cyanobacterium Anabaena sp. PCC 7120. Conclusion: NrrA controls not only cellular differentiation but also carbohydrate metabolism. Significance: A molecular network regulating glycogen metabolism in the nitrogen-fixing cyanobacteria is proposed.

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

“…The filaments were collected at the indicated times after nitrate deprivation. RNA extraction and the quantitative RT-PCR (qRT-PCR) analyses were performed as described previously (28), using the following primer pairs: RT1427-F (5=-TGCGAGTGTAGCAGAAGCAG-3=) and RT1427-R (5=-C GATACCGTAAGCATCAGCA-3=) for all1427 and RT1432-F (5=-TCTG AAGTCAGCGACGGTTT-3=) and RT1432-R (5=-CCCAATCATCCGTC ATCAG-3=) for hesA.…”

Structures of complexes comprised of Fischerella transcription factor HetR with Anabaena DNA targets

“…Two proteins, PII and NtcA, respond to the relative levels of glutamine and 2-oxoglutarate (2OG) (5)(6)(7). When 2OG is high, signaling nitrogen starvation, PII and NtcA activate transcription of NrrA (8), which in turn activates transcription of another protein, HetR, which also functions as a transcription activator. However, what creates the gradient of HetR, assuming that its activity is the critical variable in establishing the pattern?…”

The pknH gene restrictively expressed in heterocysts is required for diazotrophic growth in the cyanobacterium Anabaena sp. strain PCC 7120

“…Total RNA was extracted from whole filaments according to Pinto et al (2009) and treated with DNase I (Takara Bio). Real-time quantitative RT-PCR (qRT-PCR) was carried out as described previously (Ehira & Ohmori, 2011) using a pknH-specific primer set (Table S1). For RNA gel blot analysis, 5 mg aliquots of total RNA were subjected to electrophoresis in 1 % agarose gels containing formaldehyde and transferred to Biodyne Plus membranes (Pall).…”

“…3b). After 18 h of nitrogen deprivation, when the WT starts nitrogen fixation (Ehira & Ohmori, 2011), heterocysts were stained with Alcian blue, which specifically stains the polysaccharide layer of the heterocyst envelope (Fig. 4b).…”

“…Nitrogenase activity was determined by acetylene reduction assays using GC (GC-8A gas chromatograph, Shimadzu), as described previously (Ehira & Ohmori, 2011).…”