Phosphorus Enhances Photosynthetic Storage Starch Production in a Green Microalga (Chlorophyta)Tetraselmis subcordiformisin Nitrogen Starvation Conditions

All cyanobacteria produce a neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA). However, the biological function of BMAA in the regulation of cyanobacteria metabolism still remains undetermined. It is known that BMAA suppresses the formation of heterocysts in diazotrophic cyanobacteria under nitrogen starvation conditions, and BMAA induces the formation of heterocyst-like cells under nitrogen excess conditions, by causing the expression of heterocyst-specific genes that are usually “silent” under nitrogen-replete conditions, as if these bacteria receive a nitrogen deficiency intracellular molecular signal. In order to find out the molecular mechanisms underlying this unexpected BMAA effect, we studied the proteome of cyanobacterium Nostoc sp. PCC 7120 grown under BMAA treatment in nitrogen-replete medium. Experiments were performed in two experimental settings: (1) in control samples consisted of cells grown without the BMAA treatment and (2) the treated samples consisted of cells grown with addition of an aqueous solution of BMAA (20 µM). In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by LC-MS/MS spectrometry. Among them, 80 proteins belonging to different functional categories were chosen for further functional analysis and interpretation of obtained proteomic data. Here, we provide the evidence that a pleiotropic regulatory effect of BMAA on the proteome of cyanobacterium was largely different under conditions of nitrogen-excess compared to its effect under nitrogen starvation conditions (that was studied in our previous work). The most significant difference in proteome expression between the BMAA-treated and untreated samples under different growth conditions was detected in key regulatory protein PII (GlnB). BMAA downregulates protein PII in nitrogen-starved cells and upregulates this protein in nitrogen-replete conditions. PII protein is a key signal transduction protein and the change in its regulation leads to the change of many other regulatory proteins, including different transcriptional factors, enzymes and transporters. Complex changes in key metabolic and regulatory proteins (RbcL, RbcS, Rca, CmpA, GltS, NodM, thioredoxin 1, RpbD, ClpP, MinD, RecA, etc.), detected in this experimental study, could be a reason for the appearance of the “starvation” state in nitrogen-replete conditions in the presence of BMAA. In addition, 15 proteins identified in this study are encoded by genes, which are under the control of NtcA—a global transcriptional regulator—one of the main protein partners and transcriptional regulators of PII protein. Thereby, this proteomic study gives a possible explanation of cyanobacterium starvation under nitrogen-replete conditions and BMAA treatment. It allows to take a closer look at the regulation of cyanobacteria metabolism affected by this cyanotoxin.

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Isolation and Characterization of Two Ammonium Permease Genes, meaA and mepA, from Aspergillus nidulans

Eukaryotic Cell ◽

10.1128/ec.1.1.85-94.2002 ◽

2002 ◽

Vol 1 (1) ◽

pp. 85-94 ◽

Cited By ~ 23

Author(s):

Brendon J. Monahan ◽

James A. Fraser ◽

Michael J. Hynes ◽

Meryl A. Davis

Keyword(s):

Deletion Mutant ◽

Nitrogen Starvation ◽

Expression Profiles ◽

Optimal Growth ◽

Gene Replacement ◽

Transport Systems ◽

Ammonium Transport ◽

Isolation And Characterization ◽

Multiple Copies ◽

Starvation Conditions

ABSTRACT Ammonium and the analogue methylammonium are taken into the cell by active transport systems which constitute a family of transmembrane proteins that have been identified in fungi, bacteria, plants, and animals. Two genes from Aspergillus nidulans, mepA and meaA, which encode ammonium transporters with different affinities have been characterized. The MepA transporter exhibits the highest affinity for methylammonium (K m0, 44.3 μM); in comparison, the K m for MeaA is 3.04 mM. By use of targeted gene replacement strategies, meaA and mepA deletion mutants were created. Deletion of both meaA and mepA resulted in the inability of the strain to grow on ammonium concentrations of less than 10 mM. The single meaA deletion mutant exhibited reduced growth at the same concentrations, whereas the mepA deletion mutant displayed wild-type growth. Interestingly, multiple copies of mepA were found to complement the methylammonium resistance phenotype conferred by the deletion of meaA. The expression profiles for mepA and meaA differed; the mepA transcript was detected only in nitrogen-starved cultures, whereas meaA was expressed under both ammonium-sufficient and nitrogen starvation conditions. Together, these results indicate that MeaA constitutes the major ammonium transport activity and is required for the optimal growth of A. nidulans on ammonium as the sole nitrogen source and that MepA probably functions in scavenging low concentrations of ammonium under nitrogen starvation conditions.

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Similarities in the structure of the transcriptional repressor AmtR in two different space groups suggest a model for the interaction with GlnK

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x17002485 ◽

2017 ◽

Vol 73 (3) ◽

pp. 146-151

Author(s):

Madhumati Sevvana ◽

Kristin Hasselt ◽

Florian C. Grau ◽

Andreas Burkovski ◽

Yves A. Muller

Keyword(s):

Nitrogen Starvation ◽

Nitrogen Sources ◽

Solvent Content ◽

Space Group ◽

Space Groups ◽

Signal Transduction Protein ◽

Ligand Free ◽

Transcription Regulators ◽

Quaternary Assembly ◽

Starvation Conditions

AmtR belongs to the TetR family of transcription regulators and is a global nitrogen regulator that is induced under nitrogen-starvation conditions inCorynebacterium glutamicum. AmtR regulates the expression of transporters and enzymes for the assimilation of ammonium and alternative nitrogen sources, for example urea, amino acidsetc. The recognition of operator DNA by homodimeric AmtR is not regulated by small-molecule effectors as in other TetR-family members but by a trimeric adenylylated PII-type signal transduction protein named GlnK. The crystal structure of ligand-free AmtR (AmtRorth) has been solved at a resolution of 2.1 Å in space groupP21212. Comparison of its quaternary assembly with the previously solved native AmtR structure (PDB entry 5dy1) in a trigonal crystal system (AmtRtri) not only shows how a solvent-content reduction triggers a space-group switch but also suggests a model for how dimeric AmtR might stoichiometrically interact with trimeric adenylylated GlnK.

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Vacuolar protein Tag1 and Atg1–Atg13 regulate autophagy termination during persistent starvation in S. cerevisiae

Journal of Cell Science ◽

10.1242/jcs.253682 ◽

2021 ◽

Vol 134 (4) ◽

pp. jcs253682

Author(s):

Shintaro Kira ◽

Masafumi Noguchi ◽

Yasuhiro Araki ◽

Yu Oikawa ◽

Tamotsu Yoshimori ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Protein Kinase ◽

Membrane Protein ◽

Nitrogen Starvation ◽

Genetic Screen ◽

Vacuolar Membrane ◽

Phagophore Assembly Site ◽

Vacuolar Protein ◽

Assembly Site ◽

Starvation Conditions

ABSTRACTUnder starvation conditions, cells degrade their own components via autophagy in order to provide sufficient nutrients to ensure their survival. However, even if starvation persists, the cell is not completely degraded through autophagy, implying the existence of some kind of termination mechanism. In the yeast Saccharomyces cerevisiae, autophagy is terminated after 10–12 h of nitrogen starvation. In this study, we found that termination is mediated by re-phosphorylation of Atg13 by the Atg1 protein kinase, which is also affected by PP2C phosphatases, and the eventual dispersion of the pre-autophagosomal structure, also known as the phagophore assembly site (PAS). In a genetic screen, we identified an uncharacterized vacuolar membrane protein, Tag1, as a factor responsible for the termination of autophagy. Re-phosphorylation of Atg13 and eventual PAS dispersal were defective in the Δtag1 mutant. The vacuolar luminal domain of Tag1 and autophagic progression are important for the behaviors of Tag1. Together, our findings reveal the mechanism and factors responsible for termination of autophagy in yeast.

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Fatty acid synthase is preferentially degraded by autophagy upon nitrogen starvation in yeast

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1409476112 ◽

2015 ◽

Vol 112 (5) ◽

pp. 1434-1439 ◽

Cited By ~ 41

Author(s):

Tomer Shpilka ◽

Evelyn Welter ◽

Noam Borovsky ◽

Nira Amar ◽

Frida Shimron ◽

...

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthase ◽

Nitrogen Starvation ◽

Dependent Manner ◽

Nitrogen Deprivation ◽

Selective Autophagy ◽

Evolutionarily Conserved ◽

Specific Proteins ◽

Catabolic Process ◽

Starvation Conditions

Autophagy, an evolutionarily conserved intracellular catabolic process, leads to the degradation of cytosolic proteins and organelles in the vacuole/lysosome. Different forms of selective autophagy have recently been described. Starvation-induced protein degradation, however, is considered to be nonselective. Here we describe a novel interaction between autophagy-related protein 8 (Atg8) and fatty acid synthase (FAS), a pivotal enzymatic complex responsible for the entire synthesis of C16- and C18-fatty acids in yeast. We show that although FAS possesses housekeeping functions, under starvation conditions it is delivered to the vacuole for degradation by autophagy in a Vac8- and Atg24-dependent manner. We also provide evidence that FAS degradation is essential for survival under nitrogen deprivation. Our results imply that during nitrogen starvation specific proteins are preferentially recruited into autophagosomes

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Interaction of the novel bacterium Brachybacterium saurashtrense JG06 with Arachis hypogaea leads to changes in physio-biochemical activity of plants to cope with nitrogen starvation conditions

Plant Physiology and Biochemistry ◽

10.1016/j.plaphy.2021.07.007 ◽

2021 ◽

Author(s):

Ankita Alexander ◽

Vijay K. Singh ◽

Avinash Mishra

Keyword(s):

Arachis Hypogaea ◽

Nitrogen Starvation ◽

The Novel ◽

Biochemical Activity ◽

Novel Bacterium ◽

Starvation Conditions

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Application of an in situ CO2–bicarbonate system under nitrogen depletion to improve photosynthetic biomass and starch production and regulate amylose accumulation in a marine green microalga Tetraselmis subcordiformis

Biotechnology for Biofuels ◽

10.1186/s13068-019-1523-7 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 7

Author(s):

Man Qi ◽

Changhong Yao ◽

Binhuan Sun ◽

Xupeng Cao ◽

Qiang Fei ◽

...

Keyword(s):

Nitrogen Depletion ◽

Tetraselmis Subcordiformis ◽

Green Microalga ◽

Starch Production

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Crop production under nitrogen starvation conditions: relationships with applied organic matter and soil microbial biomass

F1000Research ◽

10.12688/f1000research.21814.2 ◽

2021 ◽

Vol 9 ◽

pp. 90

Author(s):

Masato Oda ◽

Uchada Sukchan

Keyword(s):

Organic Matter ◽

Microbial Biomass ◽

Nitrogen Source ◽

Crop Yield ◽

Soil Microbial Biomass ◽

Nitrogen Starvation ◽

Management Practice ◽

Soil Microbial ◽

Starvation Conditions ◽

Nitrogen Flows

Background: The application of organic matter with a high C/N ratio is effective for the prevention of soil degradation, although this can cause nitrogen starvation. However, some fields are highly productive under nitrogen-starvation conditions. The underlying mechanisms for this are unclear but the correlation between soil microbial biomass (SMB) and crop yield suggests that nitrogen flows from SMB to crops. We aimed to clarify this flow and the source of nitrogen. Methods: We achieved nitrogen starvation conditions by applying waste mushroom bed and repeated lettuce cropping with different crop management practices, such as watering and fertilizer application. We analyzed correlations among crop yield, SMB, and total soil nitrogen. Results: The order of the lettuce yield stably corresponded with the management practice used. The SMB increased remarkably by the time of the second lettuce cropping and showed a strong correlation with crop yield. The nitrogen from the waste mushroom bed was lost by denitrification within the crop season. The rate of decomposition showed no correlation with yield or SMB. Discussions: The crop yield corresponded with the management practice earlier than SMB. Namely, no nitrogen flow from SMB to crop. Furthermore, most applied nitrogen was denitrified and the rate of decomposition (amount of released nitrogen) not affected yield or SMB, so the nitrogen flows of applied organic matter, SMB, and crops are independent. Therefore, the nitrogen source of both SMB and crops is biological fixation. Conclusions: The correlation between SMB and crop yield is not a causal relationship. The nitrogen source for both is biological nitrogen fixation. The application of organic matter enhances this by occurring nitrogen starvation but not providing a nitrogen source.

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