Cyanophycin and arginine metabolism in cyanobacteria

Flores, Enrique; Arévalo, Sergio; Burnat, Mireia

doi:10.1016/j.algal.2019.101577

Cited by 57 publications

(49 citation statements)

References 81 publications

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“…Based on these results, we hypothesize that the cell continues to synthesize these amino acids in the dark phase and sequesters them as dipeptides to be utilized during the light phase when a fast growth rate is to be achieved. Our hypothesis is consistent with reports on another nitrogen reservoir in cyanobacteria, cyanophycin, that accumulates during unbalanced growth conditions (Flores et al, 2019). Notably, cyanophycin also accumulates during the dark condition in diazotrophic cyanobacteria, and the genes for its synthesis have been found to be maximally expressed around dusk (Li et al, 2001;Saha et al, 2016;Stö ckel et al, 2008).…”

Section: G-glutamyl Peptides Are Potential Reservoirs Of Amino Acidssupporting

confidence: 93%

Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle

Jaiswal

Wangikar

2020

iScience

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Cyanobacteria are gaining importance both as hosts for photoautotrophic production of chemicals and as model systems for studies of diurnal lifestyle. The proteome and transcriptome of cyanobacteria have been closely examined under diurnal growth, whereas the downstream effects on the intermediary metabolism have not received sufficient attention. The present study focuses on identifying the cellular metabolites whose inventories undergo dramatic changes in a fast-growing cyanobacterium, Synechococcus elongatus PCC 11801. We identified and quantified 67 polar metabolites, whose inventory changes significantly during diurnal growth, with some metabolites changing by 100-fold. The Calvin-Benson-Bassham cycle intermediates peak at midday to support fast growth. The hitherto unexplored g-glutamyl peptides act as reservoirs of amino acids. Interestingly, several storage molecules or their precursors accumulate during the dark phase, dispelling the notion that all biosynthetic activity takes place in the light phase. Our results will guide metabolic modeling and strain engineering of cyanobacteria.

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Section: G-glutamyl Peptides Are Potential Reservoirs Of Amino Acidssupporting

confidence: 93%

Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle

Jaiswal

Wangikar

2020

iScience

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“…L-aspartate and L-arginine are the substrates for cyanophycin, a nitrogen storage polymer. Cyanophycin is synthesized by CphA and then converted back to L-aspartate and L-arginine by CphB and LadC [81]. L-aspartate is converted into aspartate-4-semialdehyde, which is the substrate for biosynthesis of L-threonine and L-lysine.…”

Section: Aspartate Cyanophycin and Lysine Biosynthesismentioning

confidence: 99%

Current knowledge and recent advances in understanding metabolism of the model cyanobacteriumSynechocystissp. PCC 6803

2020

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Cyanobacteria are key organisms in the global ecosystem, useful models for studying metabolic and physiological processes conserved in photosynthetic organisms, and potential renewable platforms for production of chemicals. Characterizing cyanobacterial metabolism and physiology is key to understanding their role in the environment and unlocking their potential for biotechnology applications. Many aspects of cyanobacterial biology differ from heterotrophic bacteria. For example, most cyanobacteria incorporate a series of internal thylakoid membranes where both oxygenic photosynthesis and respiration occur, while CO2 fixation takes place in specialized compartments termed carboxysomes. In this review, we provide a comprehensive summary of our knowledge on cyanobacterial physiology and the pathways in Synechocystis sp. PCC 6803 (Synechocystis) involved in biosynthesis of sugar-based metabolites, amino acids, nucleotides, lipids, cofactors, vitamins, isoprenoids, pigments and cell wall components, in addition to the proteins involved in metabolite transport. While some pathways are conserved between model cyanobacteria, such as Synechocystis, and model heterotrophic bacteria like Escherichia coli, many enzymes and/or pathways involved in the biosynthesis of key metabolites in cyanobacteria have not been completely characterized. These include pathways required for biosynthesis of chorismate and membrane lipids, nucleotides, several amino acids, vitamins and cofactors, and isoprenoids such as plastoquinone, carotenoids, and tocopherols. Moreover, our understanding of photorespiration, lipopolysaccharide assembly and transport, and degradation of lipids, sucrose, most vitamins and amino acids, and haem, is incomplete. We discuss tools that may aid our understanding of cyanobacterial metabolism, notably CyanoSource, a barcoded library of targeted Synechocystis mutants, which will significantly accelerate characterization of individual proteins.

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“…The reason for this localization is not fully understood at this time but one possible explanation is nitrogen conversion into N storage compounds. It has been shown that heterocyte ends are the sites of accumulation of cyanophycin (Sherman et al, 2000) a polymer composed of aspartate and arginine that serves as a nitrogen reservoir (Flores et al, 2019). Cyanophycin granules were previously detected in the heterocytes of the field isolates of A. flos-aquae, yet at the relatively low concentrations, suggesting that fixed N was rapidly transported to the adjacent cells during population growth (Ploug et al, 2010).…”

Section: Re-distribution Of Fixed Nitrogen Within the Infected Filamentsmentioning

confidence: 99%

Nitrogen Flow in Diazotrophic Cyanobacterium Aphanizomenon flos-aquae Is Altered by Cyanophage Infection

et al. 2020

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Viruses can significantly influence cyanobacteria population dynamics and activity, and through this the biogeochemical cycling of major nutrients. However, surprisingly little attention has been given to understand how viral infections alter the ability of diazotrophic cyanobacteria for atmospheric nitrogen fixation and its release to the environment. This study addressed the importance of cyanophages for net 15 N 2 assimilation rate, expression of nitrogenase reductase gene (nifH) and changes in nitrogen enrichment (15 N/ 14 N) in the diazotrophic cyanobacterium Aphanizomenon flosaquae during infection by the cyanophage vB_AphaS-CL131. We found that while the growth of A. flos-aquae was inhibited by cyanophage addition (decreased from 0.02 h −1 to 0.002 h −1), there were no significant differences in nitrogen fixation rates (control: 22.7 × 10 −7 nmol N heterocyte −1 ; infected: 23.9 × 10 −7 nmol N heterocyte −1) and nifH expression level (control: 0.6-1.6 transcripts heterocyte −1 ; infected: 0.7-1.1 transcripts heterocyte −1) between the infected and control A. flos-aquae cultures. This implies that cyanophage genome replication and progeny production within the vegetative cells does not interfere with the N 2 fixation reactions in the heterocytes of these cyanobacteria. However, higher 15 N enrichment at the poles of heterocytes of the infected A. flosaquae, revealed by NanoSIMS analysis indicates the accumulation of fixed nitrogen in response to cyanophage addition. This suggests reduced nitrogen transport to vegetative cells and the alterations in the flow of fixed nitrogen within the filaments. In addition, we found that cyanophage lysis resulted in a substantial release of ammonium into culture medium. Cyanophage infection seems to substantially redirect N flow from cyanobacterial biomass to the production of N storage compounds and N release.

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Cyanophycin and arginine metabolism in cyanobacteria

Cited by 57 publications

References 81 publications

Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle

Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle

Current knowledge and recent advances in understanding metabolism of the model cyanobacteriumSynechocystissp. PCC 6803

Nitrogen Flow in Diazotrophic Cyanobacterium Aphanizomenon flos-aquae Is Altered by Cyanophage Infection

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