The cyanobacterial ornithine–ammonia cycle involves an arginine dihydrolase

Zhang, Hao; Liu, Yujie; Nie, Xiaoqun; Liu, Lixia; Hua, Qiang; Zhao, Guoping; Yang, Chen

doi:10.1038/s41589-018-0038-z

Cited by 85 publications

(99 citation statements)

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“…Furthermore, ornithine was found to peculiarly serve as the substrate for MAAs synthesis in N. flagelliforme CCNUN1 (Shang et al, ). Recently, an active ornithine–ammonia cycle was identified in cyanobacteria with the conversion of arginine to ornithine and ammonia by a novel arginine dihydrolase, ArgZ (Zhang et al, ). This gives convincing evidence for the MAAs biosynthetic pathway in N. flagelliforme CCNUN1 (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Schematic representation of the changes in expression of genes involved in carbon metabolism and nitrogen assimilation and incorporation based on the KEGG database and referred to Zhang et al, . Genes encoding metabolic enzymes are available in Supporting Information Table S12.…”

Section: Resultsmentioning

confidence: 99%

“…It can be rapidly converted into arginine by sequential degradation through cyanophycinase and isoaspartyl dipeptidase under hydration and UV‐B stress (Rajeev et al, ; Shrivastava et al, ). Based on the available KEGG annotated metabolic pathways and the newly identified ornithine–ammonia cycle (Zhang et al, ), ornithine can be synthesized by degradation of cyanophycin, followed by conversion of arginine to ornithine and ammonia by arginine dihydrolase (Fig. ).…”

Section: Discussionmentioning

confidence: 99%

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Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats

Shang

Chen

Hou

et al. 2019

Environmental Microbiology

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Summary The cyanobacterium Nostoc flagelliforme is an extremophile that thrives under extraordinary desiccation and ultraviolet (UV) radiation conditions. To investigate its survival strategies, we performed whole‐genome sequencing of N. flagelliforme CCNUN1 and transcriptional profiling of its field populations upon rehydration in BG11 medium. The genome of N. flagelliforme is 10.23 Mb in size and contains 10 825 predicted protein‐encoding genes, making it one of the largest complete genomes of cyanobacteria reported to date. Comparative genomics analysis among 20 cyanobacterial strains revealed that genes related to DNA replication, recombination and repair had disproportionately high contributions to the genome expansion. The ability of N. flagelliforme to thrive under extreme abiotic stresses is supported by the acquisition of genes involved in the protection of photosynthetic apparatus, the formation of monounsaturated fatty acids, responses to UV radiation, and a peculiar role of ornithine metabolism. Transcriptome analysis revealed a distinct acclimation strategy to rehydration, including the strong constitutive expression of genes encoding photosystem I assembly factors and the involvement of post‐transcriptional control mechanisms of photosynthetic resuscitation. Our results provide insights into the adaptive mechanisms of subaerial cyanobacteria in their harsh habitats and have important implications to understand the evolutionary transition of cyanobacteria from aquatic environments to terrestrial ecosystems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats

Shang

Chen

Hou

et al. 2019

Environmental Microbiology

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“…The same conclusion has been recently reported for a homologous protein from the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Zhang et al , ). No production of proline from ornithine was, however, observed with the whole His‐tagged AgrE protein assayed under different incubation conditions.…”

Section: Resultsmentioning

confidence: 99%

Catabolic pathway of arginine in Anabaena involves a novel bifunctional enzyme that produces proline from arginine

Burnat

Picossi

Valladares

et al. 2019

Molecular Microbiology

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Summary Arginine participates widely in metabolic processes. The heterocyst‐forming cyanobacterium Anabaena catabolizes arginine to produce proline and glutamate, with concomitant release of ammonium, as major products. Analysis of mutant Anabaena strains showed that this catabolic pathway is the product of two genes, agrE (alr4995) and putA (alr0540). The predicted PutA protein is a conventional, bifunctional proline oxidase that produces glutamate from proline. In contrast, AgrE is a hitherto unrecognized enzyme that contains both an N‐terminal α/β propeller domain and a unique C‐terminal domain of previously unidentified function. In vitro analysis of the proteins expressed in Escherichia coli or Anabaena showed arginine dihydrolase activity of the N‐terminal domain and ornithine cyclodeaminase activity of the C‐terminal domain, overall producing proline from arginine. In the diazotrophic filaments of Anabaena, β‐aspartyl‐arginine dipeptide is transferred from the heterocysts to the vegetative cells, where it is cleaved producing aspartate and arginine. Both agrE and putA were found to be expressed at higher levels in vegetative cells than in heterocysts, implying that arginine is catabolized by the AgrE‐PutA pathway mainly in the vegetative cells. Expression in Anabaena of a homolog of the C‐terminal domain of AgrE obtained from Methanococcus maripaludis enabled us to identify an archaeal ornithine cyclodeaminase.

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“…A recent study identified an arginine dihydrolase encoded by gene argZ (designated as agrE by Burnat, Picossi et al, 2019), which catalyzes the conversion of arginine into ornithine and ammonia ( Fig. 1) (Zhang et al, 2018). This enzyme has been identified as the major arginine-degrading enzyme in a model cyanobacterium Synechocystis sp.…”

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confidence: 99%

Arginine and nitrogen mobilization in cyanobacteria

Zhang

Yang

2019

Molecular Microbiology

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Summary Cyanobacteria have evolved mechanisms to adapt to environmental stress and nutrient availability, including accumulation of storage compounds in inclusions and granules. As arginine is a key building block of cyanophycin, a dynamic nitrogen reservoir in many cyanobacteria, arginine metabolism plays a key role in cyanobacterial nitrogen storage and remobilization. Recently, an arginine dihydrolase AgrE/ArgZ was identified as a major arginine‐degrading enzyme in nondiazotrophic Synechocystis, which catalyzes the conversion of arginine into ornithine and ammonia. The N‐terminal domain of AgrE/ArgZ is responsible for arginine dihydrolase activity. Burnat et al. (2019) identified the arginine catabolic pathway in diazotrophic Anabaena, which starts with the reaction catalyzed by AgrE/ArgZ. Moreover, this study identified the C‐terminal domain of AgrE/ArgZ as an ornithine cyclodeaminase that catalyze the conversion of ornithine to proline. The results demonstrated that arginine is catabolized to generate glutamate by the concerted action of AgrE/ArgZ and bifunctional proline oxidase PutA in the vegetative cells of Anabaena. These findings expand our knowledge on nitrogen mobilization and redistribution in Anabaena under nitrogen‐fixation conditions. AgrE/ArgZ is widely present in many diazotrophic cyanobacteria and may be important for their contribution to marine nitrogen fixation. AgrE/ArgZ may have potential applications in metabolic engineering and biotechnology.

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The cyanobacterial ornithine–ammonia cycle involves an arginine dihydrolase

Cited by 85 publications

References 50 publications

Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats

Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats

Catabolic pathway of arginine in Anabaena involves a novel bifunctional enzyme that produces proline from arginine

Arginine and nitrogen mobilization in cyanobacteria

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