Dataset Information

The signal transduction protein PII controls ammonium, nitrate and urea uptake in cyanobacteria

ABSTRACT: PII signal transduction proteins are widely spread among all domains of life where they regulate a multitude of carbon and nitrogen metabolism related processes. Non-diazotrophic cyanobacteria can utilize a high variety of organic and inorganic nitrogen sources. In recent years, several physiological studies indicated an involvement of the cyanobacterial PII protein in regulation of ammonium, nitrate/nitrite and cyanate uptake. However, direct interaction of PII has not been demonstrated so far. In this study, we used biochemical, molecular genetic and physiological approaches to demonstrate that PII regulates all relevant nitrogen uptake systems in Synechocystis sp. strain PCC 6803: PII controls ammonium uptake by interacting with the Amt1 ammonium permease, probably similar to the known regulation of E. coli ammonium permease AmtB by the PII homologue GlnK. We could further clarify that PII mediates the ammonium- and dark-induced inhibition of nitrate uptake by interacting with the NrtC and NrtD subunits of the nitrate/nitrite transporter NrtABCD. We further identified the ABC-type urea transporter UrtABCDE as novel PII target. PII interacts with the UrtE subunit without involving the standard interaction surface of PII interactions. The deregulation of urea uptake in a PII deletion mutant causes ammonium excretion when urea is provided as nitrogen source. Furthermore, the urea hydrolyzing urease enzyme complex appears to be coupled to urea uptake. Overall, this study underlines the great importance of the PII signal transduction protein in the regulation of nitrogen utilization in cyanobacteria.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Synechocystis Sp. Pcc 6803

SUBMITTER: Philipp Spaet

LAB HEAD: Prof. Dr. Karl Forchhammer

PROVIDER: PXD013411 | Pride | 2019-07-10

REPOSITORIES: Pride

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Publications

The Signal Transduction Protein PII Controls Ammonium, Nitrate and Urea Uptake in Cyanobacteria.

Watzer Björn B Spät Philipp P Neumann Niels N Koch Moritz M Sobotka Roman R Macek Boris B Hennrich Oliver O Forchhammer Karl K

Frontiers in microbiology 20190625

PII signal transduction proteins are widely spread among all domains of life where they regulate a multitude of carbon and nitrogen metabolism related processes. Non-diazotrophic cyanobacteria can utilize a high variety of organic and inorganic nitrogen sources. In recent years, several physiological studies indicated an involvement of the cyanobacterial PII protein in regulation of ammonium, nitrate/nitrite, and cyanate uptake. However, direct interaction of PII ...[more]

PMID: 31293555

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Project description:Plant nutrition takes advantage by the simultaneous presence of more N forms in the rhizosphere. In the last decades the interplay between ammonium and nitrate acquisition systems in roots has been deeply investigated. Although widely used as fertilizers, the occurrence of cross connection between urea and ammonium nutrition has been scarcely studied in plants, especially at molecular level. In a recent paper we provided evidence that maize plants fed with urea and ammonium mix showed a better N-uptake efficiency than plants fed with ammonium or urea alone. To elucidate the molecular mechanism underlying this response, transcriptomic and metabolomic changes occurring in maize plants were investigated. Transcriptomic analyses indicated that several transporters and enzymes involved in N-nutrition were found upregulated by all three N-treatments (AMT1.3, NRT1.1, NRT2.1, GS1, GOGAT, GDH), confirming that urea is a direct source of N for plants. Depending on N-form available in nutrient solution a peculiar response at transcriptomic and metabolomic level was observed, especially after 24 hours of treatment. In comparison to one single N-form, urea and ammonium mix induced a prompt assimilation of N, characterized by an overaccumulation of main amino acids in shoots, and an upregulation of ZmAMT1.1. Moreover even a peculiar modulation of aquaporins, carbonic anydrases, glutamine synthetase, amino aspartate, as well as the glycolysis-TCA cycle was induced in roots by urea and ammonium mix. Depending on N-form available in the external media, even changes in phytohormone’s composition were observed in maize (CKs, ABA, JA); in particular, already after 24 hours of treatment, urea induced the accumulation of trans-zeatin in shoots. Through a multiomics approach, we provide for the first time molecular characterization of maize response to urea and ammonium nutrition. This study paves the way to formulate guidelines for the optimization of N fertilization of crops to improve the N use efficiency in plants and therefore limit N losses in the environment.

Project description:Purpose: RNA-seq technology was used to profile the transcriptome of a Chinese strain of A. anophagefferens that was grown on urea, nitrate, and a mixture of urea and nitrate, and that was under N-replete, limited and recovery conditions to understand the molecular mechanisms that underlie nitrate and urea utilization. Methods: mRNA profiles of Aureococcus anophagefferens that was grown on urea, nitrate, and a mixture of urea and nitrate, and that was under N-replete, limited and recovery conditions were generated by deep sequencing using Illumina HiSeq 2000. The sequence reads that passed quality filters were analyzed by aligning to reference genome and transcript using SOAPaligner/SOAP2 (version 2.21). Results: Deconvolution and filtering of raw reads yielded a mean of 6,938,798 reads (range: 6,539,842 to 7,242,083 reads) per individual RNA-seq library (Table 1). Subsequent alignment of the clean reads to the A. anophagefferens reference genome yielded a mean of 5,852,408 reads (84.3%) for each sample that mapped to at least one location in the A. anophagefferens genome. However, of these mapped reads, only 47.4 to 50.9% of the total reads were mapped to the reference transcript for each sample (Table 2). In A. anophagefferens grown on three different N sources, 9148 to 9526 genes were detected for each sample. A comparison of gene expression among the three N sources was performed. 322 differentially expressed genes were detected between nitrate-grown and urea-grown cells, 237 between nitrate-grown and mixture N-grown cells and 29 between urea-grown and mixture N-grown cells. Fewer differentially expressed genes between urea-grown and mixture N-grown cells were identified, which further suggested the preferred utilization of cells for urea in media with mixture N. For nitrogen-limited and recovery experiments, 707 genes were up-regulated significantly, and 766 were down-regulated significantly in N-depleted cells relative to N-replete cells. N-depleted cells exhibited a broad transcriptional response to nitrogen re-addition, with 681 genes up-regulated and 874 genes down-regulated in urea recovery cells, and 312 genes up-regulated and 688 genes down-regulated in nitrate recovery cells. Conclusions: We noted that transcripts upregulated by nitrate and N-limitation included those encoding proteins involved in amino acid, nucleotide and aminosugar transport, degradation of amides and cyanates, and nitrate assimilation pathway. The data suggest that A. anophagefferens possesses an ability to utilize a variety of dissolved organic nitrogen. Moreover, transcripts for synthesis of proteins, glutamate-derived amino acids, spermines and sterols were upregulated by urea. Transcripts encoding key enzymes that are involved in the ornithine-urea and TCA cycles were differentially regulated by urea and nitrogen concentration, which suggests that the OUC may be linked to the TCA cycle and involved in reallocation of intracellular carbon and nitrogen. These genes regulated by urea may be crucial for the rapid proliferation of A. anophagefferens when urea is provided as the N source.

Dataset Information

The signal transduction protein PII controls ammonium, nitrate and urea uptake in cyanobacteria

Publications

The Signal Transduction Protein P<sub>II</sub> Controls Ammonium, Nitrate and Urea Uptake in Cyanobacteria.

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